Jason
Have you tried heat on them? Im not sure but I think a covering iron on low heat sould help them become sticky again. Ive got some that did not stick on initial contact, but are sticking fine once I heated them. Use the protective cover sheet on top of them to prevent damage. Or warm the area with a heat gun.

Try this on a sample section first!

Let us know if heat works on yours. Iam pretty sure there are alot of people in the same boat. It's funny how we buy graphics thinking we need them now, then we never get to them!
Dustin