Embarrassed candidate

Hello beautiful people, I have a question!

I had an interview yesterday and it went well, I have scheduled my final interview with them next week. Here's the thing - when I got up from the interview I realized I left a sweat stain on their white chairs. To paint the picture, this is a corporate company at their new headquarters. The interviewer noticed it as well but pretended not to. I feel embarrassingly bad, to the point where I am unsure I can return for the final meeting. Am I being dramatic/too self conscious?