I had a similar experience with the CA DMV.

I was driving on an expired license for 3 months cause I didn't realize that it was expired. For my entire life, everytime my license expired, the DMV has always sent me a notice telling me a few months in advance. This time they didn't. It was my job to know when I should renew.

So, when I finally realize that I was driving illegally, I go to the DMV, and they said that since I allowed it to expire, I had to retake all my written exams.