Sold A Car But A Year Ago But I Just Received A Violation Ticket From The Toll Roads.

Like a year ago in December 2023, I sold a car to a man that saw my car as selling. He gave me a name and his address but didn’t verify because I trusted him. I give him the title but with my info and we filled out the bill of sale that I printed out from the DMV CA website. Yesterday I received a letter in the mail stating that car used the toll roads without paying and now they are charging me a violation fee. I filled out the NRL from the DMV online and printed it out, luckily I still have it and will send back with the form stating that I no longer own that car. But I still feel nervous that the person I sold the car to never registered it and that I will be charged for any violation they committed with the car. I filled out the NRL from the DMV, we did a bill of sale I only have a copy because the buyer kept the original, what can I do to avoid future issues with this? Anyone who can advise on what to do next? I just don’t want to be related to any violations the car may be in the future.