this has happened only once to me and i have NO idea why. ill give you the replay... to be clear encase you think, i am not using any clients or hacks.
my leg was clearly on the ground

What happened is something called maxcontacts.It happens when too many parts are touching each other, and the game doesn't count any dqs. You can prevent this by trying not to get all jumbled up with the other player.

okay thanks for explaining. everyone was like >.> hax!

Ungrabbing when this happens maxes the dq'ing player dq as well.