Gladio actually does look a little upset at how Ignis inches away from him, but does his best to hide it from the man. This is all new to Ignis, and it is happening so fast that it has to be scary.

"I just... you know, exerted my dominance over you. Its a pack thing. I was worried you were gonna get hurt if you ran away from me again, and I couldn't let that happen to you."

Iggy may have seen it from Regis or Claus when a meeting was getting heated once or twice before, but it was unlikely to have affected him so much back then.