Per MLB.com and they've got something up on Athletics Nation as well.  Apparently he had a bit of a dust-up after the game last night.

Not sure if this is really going to affect the team on the field that much since he's been absent from so many games, but you have to think that this makes a lot more likely that they'll be active in the trade market.  Don't be surprised to see Dunn end up in Oakland.

Have to say that I agree with Nico at AN.  It's a head scratcher, but you have to give a GM like Beane the benefit of the doubt.