The most common reasons for it to lift:
1) The backing got contaminated during install (oils from the skin, dust, dirt etc..)
2) The wrap was over stretched in a localized area. (when heated the material will try to contract back to original form and pull it up)
3) There was existing residue on the surface (oils, cleaners etc)
Makes sense. Any way to resolve this without having to use a new sheet? My fingers were starting to feel more slippery the more frustrated I got