Hours after officially signing his L.A. Lakers contract, LeBron James and his wife celebrated in Malibu ... with his OLD Cleveland Cavs teammate Tristan Thompson (and Khloe Kardashian!).
The foursome -- along with a ton of security and others -- hit up Nobu in Malibu ... one of the most expensive sushi joints in town.
Not like price matters (LeBron just signed a $154 million contract, Tristan is in an $82 mil contract and Khloe is rich as hell, too).
So, why is Bron out with the old teammate instead of bonding with his new Lakers squad?