I believe he wasn't being sarcastic, but instead was trying to illustrate what was meant when you wrote "not uncommon". The question of what "not uncommon" meant in this context was explicitly raised, and nikanj tried to clarify on your behalf.

I'm not sure how you got such a bad read from what he said.

I'm sorry if my comment came across as sarcastic. I don't think anyone is keeping good statistics on "how often does a car get frame damage from cat theft", but I know that mechanics treat it as "not uncommon" as per my previous comment.