Scud's Studs (Week 12 @ Seattle)

[Beemnseven]

I have a question about one of the penalties against Washington yesterday: At one point in the first quarter, Helu was called for an illegal chop block on third and 3, while Grossman threw an incompletion. Immediately after, the ref said that Seattle declined the penalty, setting up 4th and 3 at the Seahawks 30-yard line. I was surprised at this, because the Redskins appeared to begin lining up to go for it on 4th down.

Then, the referree announced that the Seahawks accepted the penalty, and the Skins wound up punting. Can a team decline a penalty, then change their mind after the fact and accept it when it looks like the opposing team isn't going to punt?