Warning of a ban if the clock is left to run down rather than resigning.

I just lost the above game by resignation with 4.5 seconds left on the clock )20 seconds before my opponent moved) and nonetheless received a warning that I must not let the clock run down rather than resigning. I have never done this and nor did I do it on this occasion. A bug?

move times show you spent 44 seconds before resigning. Connection issue? Don't worry about it if you play sportsmanlike