That's... different. Well, I still don't think I'd worry so much though. Ugobes alter the pitch of their voices both when they are singing and when they are sick. When they are sick, they will sometimes fluctuate between being very deep and slow to being very fast and Chipmunk-like. I guess what happened in that case was your little guy sped himself up and... and something in his programming didn't tell him to stop playing his audio at that faster speed. What's really odd is when they start a sound at normal pitch, then rase or lower the pitch in the middle, then resume normal pitch at the end of the vocalization. This has happened a couple times with Bleu when she was sick. I wouldn't worry too much about it as the problem- if it is a problem- corrects itself on restart. Maybe your boy just wants to be a famous singer and he's practicing.
Talon