I think they're coached, or they should be, to never extend the ball into the endzone unless its a do or die 4th down play. Extending leads to fumbles into the endzone.
The timing of the calls was...odd...but MSU played very physical with the Gopher receivers and mostly got away with it until late. The Gopher D Backs didn't even get close enough to play physical in the second half!
To be fair, the PI that got reversed should have never been called. On the other hand, it sure looked like Lindsey might have stepped out...which would have been dumb as he hadn't been touched yet.