The up volume would sometimes press, and even hold. Volume shoots up to full, or, in the camera app, rapid fire of unwanted photos.
Cleaned out dust, and cleaned up the contacts on the volume buttons while I was in there. I haven't had the volume button stick since. Went great! Only possible gotcha is how I'm submitting this under anonymous666... pffff.
Patience patience patience. Small components should not be ham-fisted apart. Take the time to look at from every angle, and how to proceed. Even if you think you know what you're doing, slow down. Don't break something because you got a little overzealous. Computers are precision instruments, not rusted transmissions with decades of grime.
iPhone 4 and 4S Volume Button
iPhone 4/4S Liberation Kit