Home radiator leak question...please help

[frannn]

Our house is over 70 years old and has radiators. We have a small front "sunroom" that also has a radiator. DH thought it was turned off, but is not sure. We don't sit in the room, but I do go in a few times a day to grab DD2 a diaper. Today, I stepped in, and found two long, diagnal spots on the floor that had raised areas, like pipes running on top of the floor. I thought maybe pipes had swelled and burst, but DH said he thinks there are no pipes, but more likely warped floorboards. We have a thin layer of carpet (now moldy) over a hardwood floor. I don't recall noticing this in the sunroom yesterday, so it must have happened overnight. DH said the floor and carpet is wet near and around the radiator and the front window. Is it possible our radiator leaked or even burst enough to warp the floorboards/hardwood floor, or is there more likely another culprit? We checked the room directly underneath, and there is no leak from the ceiling (but it is covered in insulation, so it might be damp under the insulation). Should we call a plumber, or someone else? I am assuming they will have to replace the radiator, if that's what caused it. Will I need to replace my floor as well? What is this going to cost now? Does homeowners cover it?????