Apparent matchmaking bug leading to long queue times

From what I can tell, if a single player drops out in the lobby, the remaining four are put back into the queue together.

This seems to lead to more groups looking for one or two players than there actually are single players in the queue, making for long queue times.

[edit] I guess it's not really a bug, but more of a side-effect.

I find that if the queue is taking too long, and I quit and re-enter the queue, I get a match almost immediately.