I doubt that it did any damage if it happened two months ago.
Whenever a relay is energised, ie contacts are closed there is a degree however minute of arcing occuring between the contacts, this causes a furry edge to be made on the contact, the trouble is they need a nice clean surface for make/break operations.
To put it simpler they can get a bit dodgy over time, and some especially cheap ones can stick once energised(closed) they do not always open again to break the circuit, reffered to as latching.
It would be easy just to try another relay to elimnate this, doe not have to be a ford one so long as contacts are in the same position.
Some switches which again if not good quality can leak enough current through anti corrosion pastes used in them on the contacts to keep a winding energised in the relay.
Let it get to temp then pull out relay so fans stop then put back relay and see if they are still running, if now stopped you know it is a dodgy relay, unusual but certainly not unheard of.
tabetha