You should be fine. As an older non-trad, the majority of my pre-req courses are over 15 years old but I'll still be starting med school this fall. I have taken some of the other required courses in the past few years, along with higher level science courses, so this may have helped. But I would agree with
@gonnif on not retaking basic level science courses. I was worried about the age of my classes as well, and was poised to retake some of them, but am very glad I saved the time and money by not doing so. If there was a substantial amount of time between undergrad and application, and you are concerned and have the resources, then I would recommend higher-level biology courses to show you can still survive the rigors of science courses. But since the time from undergrad would be relatively short (assuming 2-4 years), I don't think you have much to worry about.
The one recommendation I would give, though, is to apply broadly when you do. Only a handful of the schools I've researched actually have an explicit time limit of courses (Duke actually removed the limit for their MD program this year, though they kept it for the MSTP), but do suspect (as others on this thread have stated) that some may have an implicit bias against older courses. Unfortunately it may be difficult to tell which ones have this bias. Non-traditional friendly schools such Case, Miami, Dartmouth, etc... are more likely to accept older courses and so would try to include as many of them as you can afford.
