Should I (33F) keep it from my boyfriend (38M)? I'd consider it an unintentional interaction.

Tl;dr Another man lightly flirted with me under the impression I was single, and I'm considering not telling my bf, that I wasn't aware. My bf and I had both purchased concert tickets for a band we both enjoy months in advance. They were meet and greet tickets, and you would get pictures taken with the band. The morning of the concert him and I got into a small argument. We didn't want to be in the picture together, and we went separately to the concert to meet the band and get pictures taken. They had us cordenate in a line, and my bf was a few people ahead of me. When it was my turn to meet the band, I mentioned I had come alone. When I had my picture taken, the lead guitarist kept stroking my sleeve, I think he was interested in me. In the picture, you could see his hand on my sleeve, It looks innocent, I'm not considering sharing pictures with my bf.

We were right in front of the stage, the guitarist had made some eye contact with me, I could sense my face was turning bright red and felt a little embarrassed. My boyfriend had been escorted to the arena area before me, and I don't think he noticed. He and I both enjoyed the concert and didn't mention anything.