Every now and again when I am browsing through a folder of shots in Lightroom it will start popping up a message 'Rendering settings changed'. Even though I have not made any development change settings to an image....Why?
any chance you've looked at the file in bridge/acr and the .xmp has new rendering instructions?
I've also seen this, and seen the settings have been changed in metadata when I swear I haven't changed anything anywhere, knowingly that is.