Kipling: This is the result of Fencer's implementation of resignation, (which is incorrect when compared to any other house of Backgammon in the Universe).

When you resign you should be asked whether you want to resign a single-game's worth (1 point), a gammon (2 points) or a backgammon (3 points). This is then multiplied by the cube and gives the number of points that you'll lose. Your opponent should then be asked whether they accept your offer of resignation (because they may want to continue play in order to win a gammon, whereas you might be offering just a single-game loss).

Fencer hasn't implemented this dialogue and thus had to make different arrangements. His answer is to examine the position and award points on that basis. This is quite wrong as far as I'm concerned but the rules are that 1) if you have taken a man off the board then you'll lose a single, else 2) if you have any men in your opponent's home table or on the bar then you'll lose a backgammon, else 3) you'll lose a gammon.

You must have had men in your opponent's table or on the bar and hence were set to lose a backgammon. Multiplied by the cube this would have been 6 points.

When your recent opponent resigned they would have had already taken a man off the board.

The important aspect of this ruling is that You must never resign a game until you have made every effort to take a man off the board, because while your opponent can make a judgement about whether a backgammon or gammon is feasible, the automated logic is rigid and harsh in its interpretation.