while parking, I accidentally scraped an unattended car.

while parking, I accidentally scraped an unattended car. A lady witnessed the accident left a note mentioning my plate number while I was evaluating the scratch. I waited there for ten minutes, then took pics of the scratch, and left a note with my contact info on top of the lady's note. After walking around for half an hour, I went back and found the owner was still not back. Then I took pic of my note and left. I didn't get call from that owner since then. I also called my insurance company and describe the details of the accident. I wonder if I need to file police a report? Would I get into trouble if the owner insists that he didn't receive my note?