and she responded asking me about what appears to be other user names linked to my own. I've only ever had one user name, never changed it.
How technical is the SP being though ?
Maybe she has had a hard time (in person or persistent harassing comms) from a punter with a username
somewhat similar to yours ?
making her think you're some one else..
Some weirdos won't take no for an answer, as in if a SP doesn't want to see them, they change username and try to resume contact