The depth of detail that we'll be exposed to during our first two years will make our college science background seem trivial. I don't think being out of school for a couple years is really going to hurt you. By this point, you've shown that you have the ability to do well by your previous performance. I think the biggest adjustment won't be that the material you learned in college is fuzzy, it's the fact that almost all of your classmates are going to be stupendously smart. Many people come in to medical school thinking that they'll be top in their class, considering that most of them were in their college. The reality is that everybody around you will have been the best in their class as well.
Nobody ever thinks that they are average. Yet, there is a high chance that you will be in your medical school class. Definetly, an adjustment.