Maybe I'm not crazy. Twice in the past couple weeks, my phone has seemingly unlocked itself in my pocket and I suspected it was to do with moisture/sweat, but dismissed it as unlikely.
In the first instance, it emergency dialed. I had just hung up the phone and put it away, so I thought I hadn't secured it.
In the second instance, I hadn't touched my phone in several minutes when suddenly my podcadt was overlaid with a demo video from an executive at my company which had opened in Teams. I closed out of that and discovered an unsent text to my wife filled with gibberish and a dozen image attachments.
I have a swipe and fingerprint enabled. My best guess is the mosture is registering my leg through the pocket and swiping it unlocked in an infinite monkeys scenario. I switched to password only for my walks now and haven't had an issue since.