Thanks to Scott at BusLeaguesBaseball, who pointed this out to me during the game.
By now we've all seen that it was reported that the coaching staff believes Alex Cobb was tipping his pitches during his start. Jim Hickey apparently took him back to show him video mid-game, but I'm not sure Cobb was able to adjust. Essentially, what was he was doing to tip was on fastballs, he would wiggle/flap/shake his glove around a la Matt Garza and Dan Wheeler. On curveballs and change-ups, his glove would remain still. Rewatching the game with this knowledge, I'd say I was able to guess with 85-90% accuracy. The times I guessed wrong, he kept his glove still on a fastball. I don't think he ever did the glove flap (baby, glove flap!) on an off-speed pitch.
This video is from the 5th inning. It was his last, so it had to be after Hickey showed him the video. But even in the 5th, it was happening. I chose this because it was one of the rare (if only) times I could get three back-to-back-to-back pitches without a cutaway and a late cut back to Cobb. It's against Mark Trumbo. Pitch one you don't get a great view over his shoulder, but the glove remains still and he throws a curveball. On pitch two you can clearly see the glove stay still before he throws a split-change. And on pitch three, after keeping it still for a second or two, he does the glove flap before delivering a fastball.
It's more obvious some other times. One on pitch, Cobb is flapping his glove before he even gets the sign (he starts the flapping, shakes Jaso off, gets the sign he wants... fastball). If you've got mlb.tv, it's worth taking a look back.