As mentioned earlier, Make a sweatbox-if you are keeping them. A tupperware cookie or party tray with lid and plastic hobby screening plus clean soap free sponges. Once they've been in it for enough time place the stamp face down on a hard surface and using tongs catch the corner of the stamp and hold it down while slowly and gently lift the glassine off peeling it back on itself. The stamp will probably curl as it dries. You'll need to press it later....good luck.
For what it is worth, every time I've encountered stuck down stamps I've tried every method known to man to separate them without success. Eventually I've ended up soaking them and ending up with stamps without gum.
That's why I don't normally collect sheets. Hard to keep in perfect condition for a great length of time. Vast area of gum that wants to react and stick to something. Lot's of selvedge to accidentily bend. I have stamps that were damaged by 'the pull' to get them apart. Like a tongue on a frozen pipe. Soaking probably is the only way, and I have some of my own to do when I get to it.