I'm guessing you should be OK, as long as they don't issue a Corrected, W-2C to you in the next couple months.
Sometimes contributions made with the final year's paycheck don't get recorded as being made until the next year because of some final year-end accounting the company is using. That could be the difference.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
