I would’ve said the same—I don’t recall having interacted with him, either. But I got the 403 Error:
You have been blocked from following this user or viewing their posts.
That piqued my curiosity, so I went for a stickybeak in an Incognito window, and his profile and the posts all looked unfamiliar.
I probably should wonder what I did, but that road usually leads nowhere, so instead I wonder just how many people he’s blocked!