OK......so this does deserve a serious answer.
I too vote for the fat as the culprit.
In the past we've a time or two gone through the trouble to actually cook up the ribs off a deer. Not a whole lot of meat on them but we had the space on the grill and it was going anyway so we cooked them.
Truth is that they were fairly good, even though skimpy. What was odd was that when we took the leftovers to work the next day for luncn, and I must say that we went at them cold, they had to be heated back up to be good. The fat that had seeped out of them, when cold, was not good at all.
Never had that problem with cold hog ribs...........