Need Xiaobaitu and Other Experts help! Urgent! Waiting on line!

I filed I-485 near two years ago (PD current in May). I just realized that I may have made a mistake when filing:

On I-485, Part 3(1)"Have you ever in or outside of US: Knowingly committed any crime of morol turpitude...". I chose "NO". But in fact, I did something wrong in the first year I came to US:
One time in a gas station, I tried to add some gasoline. I used my credit card, After filling up, I drove back to my apartment. Not too long later, a police came up to my apartment and told me that I drove away without paying the gasoline. Actually what happened is that I did not realized my credit card did not go through although I wiped my credit card.

I do not know whether this is a crime. I am worrying very much right now because my I-485 processing is delayed. I do not know if there is the cause. What can I do in this situation? Please help me! Thank you very much in advance!