Why was Donald Washington pulled for Brandon Stewart?

Shortly after he was beaten deep by Arcenaux late in the second quarter, Donald Washington was pulled in favour of Brandon Stewart. He didn't appear to have an injury issue as he was up and walking at the bench. Does anyone know if it was because of the big play, or, was there some other factor at work? Probably only the team knows for sure. I will be posting this on the Scratching Post with a suggestion that Drew Edwards ask KA. If he does ask, I will be interested in the reply.

:o

I would say he was injured as he is not practicing today

Drew Edwards ?@scratchingpost 8m8 minutes ago
#Ticats not practicing today: WRs @BGrant84, Luke Tasker, DB Donald Washington. Tasker looks like maintenance.

Drew Edwards ?@scratchingpost 8m8 minutes ago
On the plus side for #Ticats both S @CButler28 & DB Johnny Sears are doing more than last week.

Thanks Grover.