Keychain 'show password' shows an encrypted password

Hey,

I've noticed a bunch (not all) of my passwords in keychain, when I do 'show password' appear... encrypted? So instead of, say, "myVerySecurePassword123", my computer shows "13245-13245-42111". I am inspecting some "blue" actual passwords, and they were in normal form just a while ago, but now they're no longer human readable.

Does anyone have a clue as to why this happens or where to look?

All my accounts work just fine with the passwords I remember, it's just these passwords are no longer in the keychain, but have been replaced with strings in the above format. Clusters of characters, separated by dashes.

Worth noting I suspect these are passwords I have recently 'shown' - could this be FileVault being naughty?