Sure have, the one I'm using at the moment is beautiful fabric but they aren't all true 2 1/2 inch strips. Even where the fold is it is wider than the rest.
A lady from one of the quilt stalls last year told me they are all laser cut, but I don't think so or they would all be true sizes.
I love the idea of jelly rolls they are so quick to use but they seem to be getting a little bit lax at times with the cutting. *sigh*