It depends on what the score is, but I'd try to use him if it's a low leverage situation. I think he only threw 9 pitches (if they can be called pitches) in the last outing, and with the off day we can give our good pitches some well deserved rest before heading to Toronto, where we might have to fight a little harder to win.
That said, up by 4, I'd probably try to get 2 innings out of Mortensen.