I was on the same flight UA1564 on August 4th and we had something similar happen.
We were running two hours late since the inbound aircraft had an issue after pushing back that caused them to return to the gate and switch frames. We had one of the classic rolling delays for about two hours until the plane finally left Chicago. Our plane finally arrives, and we leave slightly more than two hours late. Halfway though the flight the pilot tells everyone in the exit row (21DEF) to get up and he looks out the window for a minute. This was concerning a bit, and maybe 30 min before landing the pilot tells us we have a spoiler problem and we are declaring emergency as a precaution so we can get priority. We come in a little high on approach but we land normally and we taxi to gate c19, with the fire trucks escorting us. That was a crazy flight and the plane was stuck in ORD for four days before it left again.