Grigg sneakily won a free kick and slotted a crucial goal with the tactic midway through the fourth quarter of Thursday night's 19-point win over Collingwood.
The umpire paid a free kick against Grigg's bemused Magpie opponent Brayden Maynard for "blocking" and explained the Tiger had nominated himself for the ruck.
Magpies skipper Scott Pendlebury told 3AW post-match he was concerned about the Tiger tactic.
"I don't think we want to get the game looking like that," Pendlebury said.
"All sides will see that tonight and think they can take advantage of that. Every side will think, 'Gee, we might be able to steal one if we can do this'. It might happen."