Definition
At a level of detachment or separation.
How People Actually Use It
When someone mentions a post or message and you remember seeing it but don't remember where you saw it.
"Person 1: Didn't you see that post about The Dress on Twitter? Person 2: Oh, I think I saw that at a distance. Person 1: Did you hear about that man doing yoga on the subway tracks? Person 2: No way, where'd you see it? Person 1: I don't know, I think I saw it at a distance."
Source: Urban Dictionary