Mine started popping about a year ago (I'm 35)...it's really annoying when I eat, but within the last few months I started having difficulty opening my mouth in the mornings (lock-jaw?)...so off to the doc I went! My dentist happened to also be a TMJ specialist so I've started a 3 month treatment plan where I wear a plastic mouth piece that prevents my jaws from completely closing. From what I understand, there's a cartilage bit in the joint that is actually out of place when my mouth is closed...when I open my mouth and hear that "pop," it's actually the sound of the cartilage piece popping back into place. The mouth piece actually helps decompress the joint and reduce inflammation (especially at night and while driving when my jaw is really tense). I've noticed a difference in just a couple of weeks of wearing it and hope I won't have to resort to surgical intervention!
Anyway, like you it's not a painful condition...more annoying than anything...but it really freaked me out when it got to a point that I couldn't open my mouth for a few seconds! Hopefully yours just needs a little time to heal!