Wow, amazing numbers at your age!
Only comment... personally, I also think you're sitting too conservatively with 40% of your retirement in cash and bonds (caveats follow). If you were planning to retire in the next 5 years that would make sense... however for the longer term horizon you're muting the power of compounding. If that's a short term thing, then you're attempting to time the market... which is typically a disaster in terms of long term perspectives.
Over a 32 year horizon (taking you to 65) equities have always returned between 6-9% real rate of return (it's pretty remarkable how consistent that is). You can bet on a cash/bond mix to be half or less then that. Give or take a percentage in each direction... when looking at that long term horizon you're going to see something like 7.5% (somewhere between 6.5-8.5%) return from an all stocks/equities mix and about a 5.5% (somewhere between 5-6%) return from the stock/bond/cash mix you currently have
The difference between a long term 7.5% real rate of return (inflation adjusted) and a 6% one brings your $450,000 to 4.5MM vs. 2.5MM
The part I may be missing is that you're planning to retire and pull from this account a lot sooner than 65... but if the majority of your 401K will remain invested until you're 65, then I'd recommend not having any of it in cash until you're within a decade of calling it quits. Certainly not $135,000 in cash as your update indicates - Cash is just a guaranteed net loss of inflation (a negative 3% return a year), whether it be a day, a month or a year held. Also there is almost no risk of stocks under performing bonds on a 20+ year period of time. However, if the fluctuations of the account would cause a panic in the short term, then bonds can help to reduce any anxiety of that. Studies have all shown that reactions (buying and selling) based on the market winds, is really what sinks people in the long run. Humans are just hard wired, all of us, to get this wrong. We buy high and sell low when we adjust our strategies based on performance of the market.
That said, peace of mind is a powerful thing... just seems the cash/bond mix may be pulling wind from the sails unnecessarily at this point in your accumulation phase. Best of luck to you! I'm sure you'll reach the 7 digits before 40
If it helps... my long term strategy is to move a bit more conservatively (10-20% moving to bonds) only once I've achieved the 1MM mark. I'm putting around $52,000 a year into retirement... so even if I have a down year I've conditioned myself to recognize it as a positive because I'm then buying at a discount! The power of the tidal forces of an accounts growth don't really dwarf the contributions until they get much higher. At that point I'd be concerned about the fluctuations (the downward ones) and wanting to mute them. I should get to the 1MM mark at about the age of 41. Until then I see no point to be in anything other than equities