Does any of your team have a pet out? Those seem really buggy being flagged in and out of pvp combat. Hunters, warlocks, mages maybe even.

If you're using EMA or similar addon there may be an option to flag all team as one for PvP. Pretty sure EMA has it. That might be causing everyone to go PvP when one hunter with a pet flags you.

I have never had it get stuck though.