Sure, common sense is good, but -- I say kudos to UA for calling you. We so often see people complaining about problems with their reservations that UA never caught, about having to monitor reservations closely, about partner flights not being confirmed -- and on and on and on.
It is too bad they woke you up, but perhaps the supervisor was working then and going out on vacation etc. Better to catch it and deal with it than deal with repercussions later.