Jay Gruden just took his beef with Robert Griffin III to a whole 'nother level ... firing off a shot at his former quarterback that was so petty, he actually felt the need to delete it.
If you haven't been following on X this week ... the former Washington head coach and his ex-QB have been at each other's necks ever since Gruden sent off a comment during the Eagles vs. Buccaneers playoff game Monday night.
Jay wrote on his X page, "If I ever put a QB through what Philly is putting Jalen [Hurts] through, I apologize.