I don't know if anything got hot enough to melt some sensors, wiring or switches....
Maybe the plugs fouled? (Might have something to do with running problems.)
I kind of doubt leaving a bike idling 20 minutes would do any major damage, unless it was hot to start with, and it was a pretty hot day.
Was there any 'smell' to the bike when you shut it off?
I haven't heard of anyone 'cooking' one, and have no real mechanical basis for my guesses.....