Quinn along with the others were still in Green City, and they were in Logan's lab. They were keeping an eye on the specially made device, and keeping track of exactly where Jessica went.
They were following her every move, and were waiting for Magnus to turn up. So they knew when this was the case, the tracking device which had been put in her skin under the back of her ear, so it wouldn't be found, was also able to transmit sound.
So they were able to hear everything that was going on, and that's why it was a big surprise to them all, when they heard who's name had been shouted out.
"Andy… as in Fex's son!" Quinn shouted. "Why is he there?"
"It would make sense. A lot of this matter involves those in the Vampire Corps. That was the creation of Fex and Samantha's work. As the leader, he wouldn't just stand by and do nothing. Besides, weren't you the one that told him to help out, and sent out a warning?"