The Bartender's Big Mistake... I Guess?

So here’s the story. Last Friday night at work, it was super busy. I had this one regular customer named Jake who always comes in for his usual drink, a gin and tonic. He’s been coming in since before I started working there four years ago. We’d get into small talk every once in a while... but nothing too deep, you know? Just the casual conversation kind of thing. Anyway, Friday night was hectic, really busy. Jake ordered his usual but as I mixed it, my mind wandered off and I accidentally poured some vodka into that gin and tonic instead... Yeah, yeah, I should have double-checked before serving it to him. But you know how it is when things get chaotic in the bar... everything blurs a little bit. So, Jake gets his drink, takes one sip, and his face kinda freezes up for a second. He looks at me with this puzzled expression, like “What’s going on here?” I immediately realize what happened, and I just kind of stare back at him awkwardly... Then he gives me an odd look but says nothing, finishes the drink, and leaves. The next day at work, Jake didn’t show up. Which was strange because he always comes in daily like clockwork around noon for a second round. By lunchtime, I’m starting to get worried that maybe something happened... Maybe it bothered him more than I thought? So after closing the bar on Saturday, I went over and asked if everything was okay with him. He just laughed it off, saying he noticed but didn’t say anything at the time because “it’s all good.” We both had a chuckle about it... But now that I think back on it... Am I the asshole here for screwing up his order? Should I have said something right away instead of waiting until after hours? Or did Jake just play it cool and let me off easy since he knew it was a busy night? It’s got me wondering if there’s anything more to this... What do you guys think... Am I the asshole for accidentally serving him an altered drink, or is Jake the bigger person here by not making a fuss about it? Would love to hear your thoughts on all this!