From Isaac Asimov (Little Lost Robot)
WHEN I DID SEE SUSAN CALVIN AGAIN, IT WAS AT the door of her office
Is this a grammatic error? Past simple - WHEN I SAW SUSAN
Is this a grammatic error?
No, it isn't. You need to read this in context:
It was two days before I could get to see her again.
WHEN I DID SEE SUSAN CALVIN AGAIN, IT WAS AT the door of her office. Files were being moved out.
The narrator did not see her for two days. Now he describes what happened when he (finally) did see her again.