It's a better panic than it could have been, in general. He didn't hide in a closet to hyperventilate. That, too, might be a sign of being off... or it might just be a sign that desperation to fix a problem can over-ride a panic attack.

He doesn't move away from Steve's arm, though he does hunch over a little to make sure the bag gets nowhere near it. "Careful," he warns, voice flat but expression edging into nervous.