4 units in 2 story apt.. in one apt. only when downstairs tennat turns on gas heater the wall in above apt gets hot to the touch. Could a vent have come dislodged because of a shift from earthquack? It has an attic. upstairs. I can look from there. Will wall have to be cut out to repair? is it something else. I"M the maintenance person. first time this has happened .I installed heaters only into existing vents about 5 years ago.