[Balto]

I would not be worried at all.

Getting your knee popped in just casual rolling is no big deal. It happens frequently enough to me in my joints that I don't really notice or care very much.

If you are in a heel hook or something and hear a pop, that usually means damage. Your knee will be swollen up a lot and hurt quite a bit afterwards.

However, if you are just rolling and hear a pop, it's usually just the joint cracking. There are lots of things that can cause it to crack, and if you don't have any pain or swelling, it's not a big deal.