I bought some jeans from ebay, my normal waist size and a decent quality make I've got a couple of pairs of (7 for all mankind). They arrived, I tried them on, all was good, left positive seller feedback. They were used but good condition and no obvious fading in denim anywhere.
Yesterday I wore them and as I took them off I noticed a whole (width ways) about 1.5 inches long, about 7 inches down from bum so of inside leg (not on seam). I hadn't noticed this before and nobody had mentioned it all day (though possibly because it's not in an easy spot to see).
I've had similar happen before in knees/ crotch where denim has split, but that's when jeans have been about ten years old.
Do I assume the fault was already there, or that after just one wear of the jeans, the denim has split? Seems a strange coincidence and didn't feel any tear/ split/ pressure at any point. Should I contact seller, or cut back on my cake intake 
?