going porcupine
When a person acts prickly and unfriendly towards another in a potentially romantic situation based on awkwardness and self-protection. Though person A likes person B a lot, they are afraid to show it and try to look cool by acting aloof and busy.
Don't worry, he's going porcupine because he's socially immature and intimidated by you. Give him some encouragement and he'll lighten up.