In his mailbag today Reiss seems to think there may be attitude issues, but the two healthy scratches are more performance-related.
"Andy, I'm aware of the report, citing an anonymous source, that Dobson might have "mouthed off" to Josh McDaniels. I don't know if that is true, but two people I trust who I believe are very close to that situation told me to be careful with that information. My understanding is that Dobson's lack of action is more football-based. Struggling to get open in practice. Don't do well in practice, hard to have confidence to put the player in a game. Take that for what it's worth, but that's the intel I have."
Two games for "mouthing off" did seem a little irregular to me. The mouthing off is probably just compounding poor practice performance.