Absolutely would have been above max landing weight, even with dumping fuel on the way back in. Issue must have been deemed sufficiently serious that landing about max landing weight was required - there almost certainly would have been a discussion between the flight crew, flight dispatch and maintenance control to agree on this course of action. Landing above max landing weight may require a post landing inspection before the aircraft can return to service. Landing with a gentle sink rate versus planting it on is much preferred in this situation to avoid stresses on the airframe. Nothing inherently dangerous with landing above max landing weight, especially with the long runways at ORD.