Pet store mice okay?

I'm a teacher and have a 1 year old cornsnake in my classroom. I purchased her at a very reputable vivarium that's an hour away. When I went to pick her up I bought 3 months worth of frozen pinkies as well and i'm down to my last few.

We have lots of pet stores 5-10 minutes from us and I'd much rather go to one of them to get more feeders than an hour away.

I know not to buy snakes from PetSmart, Pet Co etc, but is it okay to buy the frozen feeders from them?

Thanks!