I've made a few signs so far, including a fairly large one and everything is going fine, but today I had to peel up a graphic that I had just applied and I was startled to find how easily it came off. Once I got a corner up I was able to just pull it off with very little effort. So I was thinking that the adhesive isn't sticky enough, but that can't be the case obviously, since the vinyl is made expressly for this purpose. My question is, does the adhesive set up and bond to the surface better after a little time?