With Trunks no longer being able to work more than as a contracted-consultant at Torchwood anymore, opportunities to interact with people there and to go to Everglade were less. So it had been a bit since he'd interacted with Koishi, given her tendency to come and go as she pleased. Sadly, because of simply what she was and how that worked--he couldn't even necessarily brace himself by sensing her. So when the hug happens, it's probably going to skid a bit on the floor and hopefully not fall over.