If you're gonna call time out, just challenge. It was a horrid spot. We might get another half yard anyway. Won't get on Rex too much for that though. EDIT: Upon further review, what am I thinking, why are you using a time out in the 2nd half in general, he has to be decisive.
The play call Miami would do more times than not with Marino in this situation was the play action fake dive into the middle with the TE coming across the middle for ridonkulously long runs after the catch on 4th down.
You only get 2 challenges per game. And he didn't get the 1st down. It was clear on the replay. Maybe that's what he's thinking.