This has happened to me at least twice, possibly three times. It may be an error, it may be a dropped connection, or they may be doing it on purpose to "bump down" my score.
When in the first menu, where you can edit time, squadron size, arena size, etc., if the other person disconnects in that screen, it still counts as a "tie" even though the match did not begin.
So, maybe change it to where ties can't be done via forfeit? Or, at least, no ties or scores can be ranked from the beginning menu screen before the match actually begins. This has made my score 18 wins / 28 games, when it should be 18 wins / 25 or 26 games. (Not requesting a score change, just reporting the bug.)