This has happened a few times over the last month. If I park facing uphill and leave it in gear, sometimes when I take my foot off the brake and clutch the jeep will roll back a few inches at a time. Sometimes it just does this once, sometimes it does it a few times, a few seconds apart. It's a 99 TJ 5 spd AX5, about 85K km on the original clutch. I'm hoping the clutch is the problem and not the tranny/t-case. I've gone through the FSM but can't find anything related to this...any ideas?

what gear are you parking in? How steep are the hills? Cause it sounds to me like the jerking backwards is your engine hitting compression stokes. Nothing wrong with that just try you park brake too.