My daughter used to do this when she woke up from her nap from about age 2- when she dropped her nap at about 3.5. Nothing I would offer her or try to do would settle her down. She could not seem to get going after her nap. I let her watch tv for a little while and all of a sudden she would snap out of it and be her usual self. I think she just needed to wake up more.
The worst was when we had to get her up and head out the door right after nap. Asking for trouble.
She never had night terrors but was not a great night sleeper until she was almost 3 and had all her teeth. We also had never sleep trained her.