I took all my pre-reqs at a community college as well. Graduating from a private undergraduate institution with none of the pre-reqs fulfilled, there was no way I was going to spend 4x the amount to take the classes. Also, most 4 year schools want to charge you non-matriculated rates because you already have a BA. Even the state schools are ridiculous. When I spoke to the schools about where I was taking classes, they told me as long as I got a B or better in all the pre-reqs it was fine. They are more forgiving if you get a C on a pre-req from a 4 year school.
I've been asked why I took the classes in my interviews and have told them the truth every time...it was cheaper!