Help with cactus wraps

[Coffeemug1]

We have been using cactus wraps for about a year, but everynow and then we get a blue tinge around the rim of the mug, at the cornners or all the way down the side of the mug,, is this from the blow out paper? Wraps being to tight? not tight enough?
anyone that has had the same problem or knows what to do,, and Help would be great..
we are at a loss here,,,
Coffeemug1