I said no to AI Art

I said no AI generated character art and all my players submitted their character art. Since this was toward the beginning of the campaign, and I was busy, I didn't check their art---I just trusted they wouldn't turn in AI art. We did session one and I realized one of them did use AI art.

I want to tell her she has to get other art for her token but I know she was complaining so much about how it was so hard to find yellow tiefling art. I want to stick by what I said but on the other hand it is just art; what should I do?