When I checked in for my flight yesterday in SFO, I heard a conversation between the MOD and a flight attendant about the situation. The crew was USAir. The flight attendant was trying to take the stroller away from the passenger and they got into a tug-of-war. Then, the flight attendant let go of the stroller and the passenger was hit by the stroller. The incident was definitely handled very poorly, but the passenger is also at fault.