You may be over thinking things. One off day could be just one off day. If a pattern sets up that's something else but right now I would say just relax about it. I might just be an annoying person who doesn't make a big deal about maintenance. I find that as long as I keep eating pretty much how I ate when I was losing weight I do pretty well. I may eat a few more carbs and a few more calories but really there's not much difference between losing and maintenance for me. I did switch from three meals per day to two meals per day but the amount of food I eat has stayed pretty much the same. I try to stay vigilant but relaxed, meaning I continue to pay attention to what and how much and when food enters my body but having figured that out I also try to relax around it. Sometimes the scale goes up a bit and sometimes it goes down. I can't always tell why. Our bodies are not precision machines. Keep the food steady and the body will find its own level a long as you keep eating low carb/keto or at least that's what I believe.

Jean