I witnessed a match between players "andybb" and "goforfun". Nearing the end of the match, with goforfun as the clear victor of the match, andybb begins to abuse the pass/mark live stones abuse. During the process, goforfun had about 14 seconds while andybb had about 3 minutes in their respective timers. Suddenly, something unexpected happened: a few moves after goforfun had captured all of his opponent's stones, the match concluded in a draw. 

Neither player had issued a draw.

Is this some sort of bug?
Or is it a feature that was implemented on purpose?