I'm not going to ask for anything. The captain was checking over the plane and found something he didn't like, so he rejected it. I personally don't want to do anything to discourage that behavior.

Technically, missing my first return flight - the one that was shockingly on time - was my fault. But it was definitely my fault I missed the second return flight. I was catching up with an old friend over coffee and completely forgot to leave for the airport. (And, of course, once I got there the flight was on-time.)

I have zero complaints about United right now. They've been very understanding and reasonable lately. One the reasons they're getting all of my flying business these days.