Jason,
In my personal opinion, feeding frozen rodents are fine. I personally feed frozen. Most pet stores and whatnot (atleast in Ohio) will not sell live animals to people as food items. Specialty stores as far as I know will often sell live food that is usually bred for that purpose. I only feed live rodents to my burmese, and that is basically because she refuses pre-killed. Otherwise she would be eating them frozen too. Frozen rodents are easier to keep in stock without having to run out to the nearest specialty store every time you need a rat for your caiman. I am certainly not a reptile health expert, but in my opinion, your frozen rodents are fine. If you would like to help out with vitamins or anything, you might want to try a vitamin supplement, like "miner-all.
I hope this helps in some sort of way or fashion.
Chris