I know this is different, but some adcoms think that people retaking a 30 MCAT, a good score, is just arrogant.
Now, I'm not an adcom. But if I saw your good 3.76 GPA and then I saw a bunch of random classes I would question why you took them and if you were just trying to pad your stats. If you took them because you are passionate about learning, then that is cool, but it won't really boost your chances in the application cycle. Otherwise I think it would be pretty much neutral and getting your GPA up into the 3.8 range would marginally help you.
I would instead focus all your energy and time towards getting a great MCAT score. That seems much more worth your hard work and will make a meaningful difference.