causes for sudden stress?

[poomwah]

George (white sided rat) is usually pretty laid back. My daughter had him out earlier tonight and told me that he struck at her. She swears she wasn't doing anything differently than normal. No sudden movements, she was holding him and he suddenly hissed and struck toward her face.
That is VERY unlike him. That was about 8 hours ago.
I just went to get him out and he shot out of my hands to the opposite end of the enclosure. He sat there watching me intently, breathing heavily, and "rattlesnaking" his tail. He is incredibly stressed.
What could cause such sudden stress? Temps are same as usual. There hasn't been any more activity in the room than usual. I can't think of any sources of smells that would trigger any type of fear or stress. But the poor guy is scared to death. Tomorrow is feeding day for him, but I'm not sure I want to mess with him if he's that scared.
Like I said, its just so unlike him.
Obviously he needs to be left alone for a while, but is there anything I should check ? anything I should be looking for?
Thanks everyone.
George is male, 20 months old, fed FT, eyes are clear