Aye, I get that. It's just so uncanny that it's totally fucks your mind.

Probably the same reason a lot of people are duped by unscrupulous mediums and such. Our minds just can't accept that they know all this information from out of nowhere. In an unscrupulous mediums' case could be phone research or filled "secret" questionnaires or secretly recorder prayers or whatever.

And in your case maybe information osmosis, or someone who knew a lot about you happened to talk to that person. I remember when I was young I bumped into a neighbor I hardly knew and she was asking and talking about a whole lot of personal stuff that was going on in my life, and I was kinda like wtf how did you know and walked off in a half-dazed wtf ... then found out weeks later she'd jumped bumped into my mother literally 10 minutes prior to bumping into me and none of them mentioned it. And I was like oooohhhh ... click.

Not discounting your own experience of course, just offering up some plausible explanations. Anything is possible.