The moment Gyre says it's a little creepy, Seth just, deflates. Pretty much completely, hanging his head. The shrug and the latter statement is barely a consolation to him.

He should have known...how could he have forgotten how others tended to view his hobby? Zafika had been fine with it, but even they had only seen Abigail.
He still wanted to be Gyre's friend, after all he'd been kind enough to help him, not to mention know how to actually sign...but he was admittedly hurt that Gyre too found his hobby creepy, even if only a little.

"Oh...I...see..." His signing is slow, his hands faltering.