ESPNBoston.com's Mike Reiss might have discovered the trigger.
Reiss, citing unnamed player sources, reported Moss and quarterbacks coach Bill O'Brien got into a heated exchange at halftime of Monday night's victory over the Miami Dolphins in Sun Life Stadium.
One of Reiss' sources described the verbal altercation as an "outburst" in the visitors' locker room. The story also noted this wasn't the first sign of friction between Moss and O'Brien, the de facto offensive coordinator.
Moss didn’t have a catch at halftime and had been targeted only once. Tom Brady didn't throw to Moss for the rest of the game.
Two days later, the Patriots finalized a deal that sent Moss to the Minnesota Vikings for a third-round draft choice.