If I understand what you're saying - if it was showing up on the thread with <<deleted>> then that would mean I deleted it.
But it doesn't show up that way on the thread I posted on. When I do a history of my past posts - "my messages" - then it shows up there in red. When I click on it, it says "(deleted post)" under the subject.

Would that happen if the post I replied to was deleted by the person who wrote it?

Or does it make a difference if it was a reply to someone who posted their post as friends only?</deleted>