Comiserations, SubaruWolf. Stickers can be a real pain, even if you apply them yourself when the set is new (don't get me started on stickers inexpertly applied by children on secondhand lots...). I think the quality of stickers varies quite a bit.
As Raven said, extra glue may solve the problem, but its not always reversible. I guess you could try warming the sticker gently with a hair drier to soften the glue slightly, then press it down again.