Check engine light

The day after I had my smog test and passed the check engine light came on. Smog station said it was a coincidence and I should go to the Toyota dealer to have it checked. They said that the hose from the charcoal canister to the fuel tank was disconnected causing the evap emission control system to malfunction. Was fixed but I would like to know if you think this was caused by the smog station because I wanted to be reimbursed for what Toyota charged me but they still said they were not responsible and held to the story it was just a coincidence that the check engine light came on the day after the smog test. Thanks