i'm far, far, far from an expert. i'm interested in figuring out why this is, too, because it just seems to happen sometimes for no apparent reason.
at first, i had all kinds of burn problems because i was smoking them too wet and also had a ceiling fan blowing (on high) right overhead. doh!
but i've got my cigars as stable as can be, and i've learned quite a bit about factors that can screw up a smoke and avoid them now. still, every now and again i'll have a wrapper split -- or it starts to unravel about halfway through (i keep the bands on now until i absolutely HAVE to take 'em off, and that helps.
it seems to just be the case that some wrappers are heartier than others. CTSH seems to be the most delicate and thin. i love them, but i can almost count on them cracking or coming unraveled at some point. whatever the wrappers are on henry clay and punch, they seem to be the heartiest/thickest.