My ZJ Grand Cherokee did this. Then it started to pop semi-quietly (binding) on slow turns (like into a parking lot). Then a loud bangs before we finally caught it.
So you can wait until it makes MORE noise, but I wouldn't want it to fail on I15 (assuming you are on the Wasatch front). My ZJ had a blown boot, so it was rather easy to see once we knew what we were looking for.
Problem is, how is the hub design on the RRC? On the D2 it requires an unearthly amount of torque to get the hub back in. If the Classic requires a similar amount, I'd do the hub and wheel bearing at the same time just so I didn't have to source another 360 ft*lb torque wrench and breaker bar!
Just did a quick check assuming the classic is like the D1 appears to be around 61nm (whatever that is in "real" units
). In that case, easy fix...like my ZJ, we had it in an out in under 30 minutes and that was my first axle ever.