Jaylen Brown dunked on LeBron James. Brown caught LeBron during the third quarter as the Celtics were extending their lead. Brown was understandably excited about the dunk, combined with the atmosphere and yelled as he hung on the rim. When he came down he looked at LeBron and ended up getting a technical.
It was an incredibly weak technical foul. If you can't get excited about dunking on LeBron at home while on the verge of ending Kemba Walker's winless streak against James, when can you? This wasn't even trash talk. There was no reason to fear escalation of any sort. Referees need to chill.