I am such an idiot ... I left my salon without tipping my hair stylist. What do I do?

I have a lot of stuff on my mind and it completely didn’t occur to me until just now (10pm!).

I paid with a Groupon (pre-purchased salon credit) and I guess because I didn’t take out my money/credit card, I just didn’t realize. I feel like a complete schmuck!

I am obviously going to go in first thing tomorrow and tip her but should I bring her coffee? Should I add/message her on Facebook tonight?

I’m going to lose sleep over this!