Jack finishes looking around and looks back at Serph, and his tails wag happily at the peaceful expression. He pads over and leans against Serph's hip and thigh, unable to hug in this form but ready to show affection. "It's a wonderful place. I can imagine you'd want to dream of somewhere like this a lot."

It must be somewhere the human version of him had been. That's the most likely explanation. A leftover memory of somewhere happy.