One issue to consider, although it's unusual: I slacked off some during my senior year. I had already applied to grad school, so I figured it didn't matter. I actually didn't slack at all. I got married, I had pneumonia the week of exams, I was commuting 3 hours each way second semester, etc. Except obviously these are just excuses, and in the end it's my fault I didn't do better.
So, guess what? I hated grad school, dropped out, and decided to apply to med school. Oops! Now my senior year grades really matter.
Obviously if you're already accepted to med school, it's unlikely your senior grades will ever matter again in your life. On the other hand, you never know. It's probably worth doing as well as possible just in case. Not that you have to get all As, but I would try not to get Cs. It won't be the end of the world if you do (I did), but you'll be more secure if you don't. Besides, it feels good to graduate with honors, and it really sucks to graduate .01 grade points away from a higher level of honors just because of one C! 😛