Bitlocker and unencrypted key traces

Let's say a Windows drive is encrypted from within the OS, with "Encrypt used disk space only". Is it possible that some unencrypted data about any of the protectors (like password or recovery password) is left behind?

On an SSD the data usually isn't overwritten if there's free space.

I guess Bitlocker isn't stupid enough to write unencrypted keys to a not-yet-encrypted drive directly. But maybe the keys are in RAM and then they end up in the pagefile? Is …

bitlocker computerforensics key traces unencrypted