Either he's mad at GP for not resigning him (like me), or he didn't want to come back for the following reason:
http://blog.mysanantonio.com/spursnation/2010/11/25/neal-clutch-times-three/
REFRESHER COURSE: New/old Spurs swingman Ime Udoka says it isn’t difficult to erase the remnants of the Sacramento Kings’ system.
“It’s not hard to forget that,” said Udoka, 33, who spent last season with the Kings after two with the Spurs. “It was a lot of standing around.”
Signed Wednesday to a veteran minimum contract, Udoka doesn’t think it will take him long to re-learn the Spurs’ system.
“There’s still a ton of plays, like always,” Udoka said. “It’s just a matter of refreshing your memory.”
http://blog.mysanantonio.com/spursnation/2010/11/25/neal-clutch-times-three/