The LOX thread seemed to get more into rosebud issues, so....
I was going to call this "Torch Tips" but that seemed somewhat too punny.
When a torch pops, the flame has extinguished downstream (outside) of the tip (due to that lower velocity previously discussed) and has progressed upstream...INTERNALLY! Now once this happens, damage results inside the torch tip (rosebud, blowpipe/brazing tip, or cutting head). Oftentimes this damage (and resultant carbon build up) to gaskets and seating surfaces is a non issue...until the next pop, and the next...Once it happens, the torch is more susceptable to backfires and so happens more often and easier.
NMWELDER, Is acetylene harder to light??? Can't say I've noticed any difficulty as you describe. All problems I've had to adress seem to iron themselves out when proper procedures and equipment are used and followed.