Doonesbury does it -- do you?

Several weeks ago, when "Doonesbury" showed Grandma Joanie proposing to move in with Alex, faithful correspondent JHM wrote to comment on a usage in the strip's dialogue. Joanie offers to help Alex pay her rent. "Wait, is there a hitch?" asks Alex. And there is: "I'd have to move in," says Joanie.

For JHM, hitch wasn't quite the right word. "I would've used 'catch,' as in a deal with strings attached," he said, adding a definition from Oxford Dictionaries online: "a hidden problem or disadvantage in an apparently ideal situation: there's a catch in it somewhere."

I would like to say that yes, I too would use catch, not hitch, in this context, and I'm pretty sure I would:  I think of a catch as a preset trap, a hitch as just a random snag in the proceedings. On the other hand, I read right past the hitch in the Doonesbury cartoon, speeding onward to the punch line. So it's obviously not a red-flag distinction for me.

After a quick and unscientific glance at Google News sources, I'd venture to say that the catch-hitch distinction -- as JHM and I make it -- is widely observed: I found catch almost always used to imply a hidden clause or condition, hitch used mostly for "unexpected problem," usually in variations on "it went off without a hitch." But I wonder -- if hitch did start migrating into catch territory, would we notice? Did you?