That could have come back to haunt us. You can't just throw the flag because it "looked" like it was loose. It was obvious from the replay that there wasn't anything conclusive so I'm not sure what Sherman saw and I think he was just reacting because of the first down.
Pete needs to consider the value of what the challenge will bring, and he needs to hold on to that flag unless it's got a good chance of being overturned, which means he needs to have an obvious view of something like the ball on the ground.
He's done this in the past and said "I got hormonal but now I have people there to stop me." Not Sunday he didn't, and he should have.
As a rule referees don't like overturning a call, so the odds are immediately stacked. What if Russell Wilson threw an "apparent" pick six that lost us the game but with instant replay it showed that the ball hit the ground but we had no challenge because Pete used it to challenge a first down?
IMHO, challenges should be used for game-changing plays, not to determine a first down early in the 2nd half.
But Pete's not the only one who does it. Arians got away with throwing a challenge flag on a turnover because his Olineman picked it up before the referee saw.
I think it was Lovie Smith that threw an illegal challenge with less than 2 minutes and the referees let him get away with it.
And was it Jim Schwartz that threw the illegal challenge flag last year that resulted in Justin Forsett being awarded a touchdown that wasn't?
Pete's got to more cognizant of throwing that flag before it costs us the chance at a 2nd Lombardi.