..., and I've been working on picking and holding steady lines, working on my balance, working on apexing, working on countersteering/leaning etc. But I clearly need more practice at it, so that's what I'll do. Thinking about it more, it very well could've been the painted lane stripe on the bike path there, I slid right as I was apexing in a left-hand turn, and I may have touched that line while apexing. Or, I just plain messed up and I need to keep practicing. Or both...
You're overthinking it. You're just riding a bike. Have fun. Ride at a level you're comfortable with and skills will follow.