Anyone else had a problem with Safe Cat breakaway collars?

We've been using Safe Cat collars on several of our cats for years, but have run into an unusual (?) problem. We apply Advantage topical medicine on the back of our cats near their shoulder blades monthly to control fleas, ticks, etc. We just found one Safe Cat collar where the release mechanism seemed to be glued together-presumably from contact with the medicine. We had to cut the collar off as we couldn't pry the release apart. It could have killed our cat if it had become hung-up on something. Anyone have similar experiences? We're just trying to determine if this could be an ongoing problem.