are you the only owner?

cold setting a steel bike 4mm takes a little effort. i wouldnt be surprised to see a cannondale crack or kink if it were "cold set" 10mm. keep in mind you would have to spread it past 140mm to make it stay there. some tandem hubs are 145mm. if a previous owner shoved one of these in the bike it may have cold set the frame to 140. ive got a bike (steel) that was 126mm but is now about 128mm from years or removing and replacing a 130mm hub.

your decision to quit riding the bike is a smart one. hopefully you can get it replaced (if you are the original owner)