Thanks for the reply. I'm not sure what brand they are, but I got these from CT Rogers last year. They are a thinner type of flip. I also have some thicker flips that I bought from a local coin store, and those are fine, no sticking problem with those. Both are the 2.5x2.5 flips, but the cardboard is thicker on the flips that I got that don't stick on the outside.

Did your flips only stick on the outside, or did they stick on the inside too where the chip is? I don't think the insides on my problem ones are sticking as I am able to move the chip around inside.