One of my LoRs was from a former military commander I had back when I was active duty. It was probably six years old when I submitted it (and was non-specific to med school, obviously) and it didn't seem to hurt my application at all. Although recent LoRs will obviously be necessary (and I certainly had those also), if you want to get a letter from current professors, I don't see a problem with it. Just bear in mind that with that amount of time off between undergrad and medical school, you'll need to be looking for letters from managers/supervisors of whatever you do in the meantime.
Good luck.