A Tipping Mistake at Work

So I've been working as a bartender for about three years now, and I thought I had everything down. Regulars know me by name, my drinks are always poured to perfection, and every night is another adventure in customer service. One thing I never really got used to was the constant pressure of making sure tips were fair, especially on busy nights when everyone is trying to get their attention at once. Anyway, last Friday was a particularly hectic shift, more people than usual, so many drinks ordered and served. I had a regular named Dave who always visits around 9 PM on Fridays. He comes in with his group of friends every week, orders a few rounds for them, and leaves a generous tip at the end of each night. This time though, things got hectic after their round was placed. A lot happened between pouring other drinks, cleaning up spills, answering phone calls from delivery drivers... I managed everything well but when Dave's group left that night, I must have been so preoccupied with all the tasks at hand, I completely forgot to add their tip to my total earnings for the night. It wasn't until I was clocking out and double-checking everything in our system to make sure no one cheated me on anything else that I noticed. The numbers just didn’t match up. A quick recount of all tips left behind confirmed it: there was an extra $50 from Dave's group sitting where no one would have seen it but me, while my total showed a deduction for their tab instead. I could not decide whether to return the money back with another note or just leave it at that. After tossing this idea around in my head all night and half of Saturday morning (which is when I officially realized what had happened), I decided against going back because the thought of how it would look like me taking advantage of their mistake just stuck too much. Then again, maybe I'm overthinking it? Or perhaps I should have gone with an honest note attached saying something along the lines of 'Sorry, my bad.' Whatever the case is, here's hoping Dave’s group doesn't check their wallets until after they've had another round of drinks next week, and if they do find out earlier somehow... well, let's just hope for the best. Anyway, that's how a bartender could lose count on busy nights. It's like those moments when you forget your own phone number but know everyone else’s by heart; it happens sometimes.