If he was, he wouldn't have been an expendable QB3. Also, they don't have any sort of a real backup for Willis.
The same could be said for Zach, sure, but he'd be a fairly cheap pickup for a guy who has shown he's got the potential.
The way Love walked back to the locker room makes me think it's not serious and hopefully so. But if it is, GB will be looking and Zach is certainly a possibility.