How is this checkmate ... or does chess.com have a bug? Playing as black against the chess.com computer, the following position was reached and chess.com declared checkmate in its favor. However, I don't see that the black king is in check. So is this a bug?

[FEN "2r2r2/p6k/2b1p1R1/2pp2Qp/P2P4/1PN5/1K6/8 b - - 0 1"]


There was no time limit in effect and this is the final position. There was a message that said "Checkmate" and I couldn't make any more moves. (White's last move was Qg5; it had been on h4.)
Obviously, this is not a checkmate. Something else must have happened. 
Here is what I could imagine:


Maybe you have lost on time, and not by checkmate
Maybe this is the position before White's last move (Qh6# or Qxh5#), which was played a mili-second before the computer claimed victory - so that the mating position wouldn't have been visible on your screen for long enough for you to notice.
Maybe (but unlikely) there is some bug in the software. Possibly the software 'played' Qh4xh5# but somehow sent Qh4-g5 to the virtual board for unknown reason.