Sounds like the form is sent early and then revised if necessary: (quote is for an earlier yr but you can adjust mentally)
http://www.alvinisd.net/cms/lib03/TX...oshure%204.pdf
2. IRS Form 5498-SA (Contributions)
The form, sent in January, provides you with all the contributions made to
your HSA in 2013. HSA contributions for the 2013 tax year can be made
up until April 15, 2014. (Note: The IRS does NOT allow an extension of
time to contribute to an HSA, even if you have an extension for filing your
taxes). If you make additional 2013 contributions in 2014, an updated
IRS Form 5498-SA will be available between April 15, 2014 and May 31,
2014 as a confirmation of your total contributions attributable to tax year
2013. If you did not have contribution activity in 2013, you will not receive
an IRS Form 5498-SA.