Got on this morning, started to push backwards out of the garage, noticed it was very hard to push, checked it out, rear tire is flat.
No idea what happened. I never noticed running over anything. I haven't ridden it in about a week since I was out of town so I don't even know if it lost air gradually or what.
What a bummer! I'm not even sure how I'm going to get it to the shop to get it fixed.