I experienced similar things in the past.On a different forum I one day had PM's from someone that I had obviously been conversing with for awhile.I had no clue who they were though and had no memory of it.It shocked me.I wasn't sure what to do so I replied and acted like nothing was out of the ordinary.My T called it "bumping into myself" and thought it was a good thing because I was becoming aware of my dissociative experiences.

So even though you were shocked maybe it's good that you're able to recognize there's some disconnection going on?