We saw this same issue with a jedi consular in our group running Hammer Station. He was in stealth mode and standing next to all of us and there was no aggro. Suddenly, his stealth broke and the mobs down the hall aggro and jump us. He never moved, just that stealth popped. This happened 2 more times before we figured out what it was and told him to not stealth. Then everything was fine, no aggro even standing in the same spot.