It is certainly not because she is female, because so am I (and have been told I'm very "feminine") but these small things do not worry me at all.
As you are no doubt aware, Moms never stop worrying about their kids, even when Mom is 85 and the kid is 60. But that doesn't explain worrying about a fifty-cent gas coupon.
Some of what you describe, sounds less like "worrying" and more like the way a detail-oriented person plans out her day. If she likes to do her planning out loud, it may sound like fretting to you. But I would see it as exercising her strength of paying attention to small details.
I have no idea what effect a "conservative" upbringing would have on anything, but that's probably because my parents were middle-of-the-road politically, as am I.
I think you are onto something. DW is a serial planner, one reason being I think she is not good with change, or moreso surprises or unplanned things that spontaneously come up. She has 2 planners, plus our Calendar she and I share to write down obligations throughout the month/year. I can be spontaneous without bother, or worry. She on the other hand always starts tossing out a bunch of questions, which is fine but hard for someone with my personality type to always understand. I think in one way that is the beauty of being around people different than I, that I do learn things from them. It's interesting because we are complete opposites on many regards, but our core values are 100% aligned. I always sort of use the analogy that "there is more than one way to get the dishes clean, and none of them are incorrect". Two different paths will often lead to the same destination/outcome, just a different adventure on the way. I try my best to communicate things as soon as they pop up but since its not my nature to plan out everything ahead of time sometimes I admittedly am the reason for her worrying. We always have a hard time planning trips because her initial fears/worries overwhelm the idea or discussion on where to travel etc. Then, once we start planning it out she sort of "comes around" to the ideas of travelling. I do also think a lot of it is being the "mom" role and I get it. As a father, I have certain values and objectives as I raise my children and she has others, but together, we make a really strong, really solid, really great team. Sometimes it just takes a little conversation and adjustment for us to get to where we are going is all.
It's funny, someone above mentioned the cooler...my wife TOTALLY came up with that solution on her own yesterday and decided to take a cooler with her to CostCo/Wal-mart so the cold items stayed cold. I think our wives would get along GREAT with each other. Me, I just let the stuff get warm knowing it will be in the refrigerator soon enough.
In terms of the conservative thing, its probably more the opposites attract thing again. My parents raised me somewhat middle of the road, but liberal leaning, whereas her parents and especially her mom's influence put her in the more conservative leaning camp; I'm not talking politically specifically, just that they are not quick to make spontaneous decisions, they plan a lot of stuff out, they enjoy familiarity without much change (her mom has worn the same outfits and the same clothing style ever since I met her 15 years ago) so they very much know what they like, and more so don't want to worry about change so they don't change things around much. My dad bought a sailboat out of the blue one day. He took us on spontaneous camping trips or road trips that he hadn't planned out much where we just kinda went where the road and wind blew us. So I was raised much differently in that regard...maybe conservative vs less conservative isn't the best term for that, though.
DW does enough worrying for the both of us. She also is very quick to be like "I told you so!" lol. But I still love her for who she is.
A while ago my DW was super worried about the kids having any sugar before bed, and it caused a bit of a "debate" when I gave them the Crystal Light drink. I had to politely remind her that Crystal Light was sugar free. She knew it was sugar-free, she is the one that bought it for that reason, but I think the idea that it was red, and looked like the cool-aid or whatever that isn't sugar free was enough for her brain to sort of trip up and start the worrying. BUT...we started googling, or maybe she did (hehehe) and discovered there are "other" bad things in that drink, so it really didn't help my side of the debate much.