I often get a message saying one of my posted has been deleted because they are off-topic or for some other reason.
What's the implication of this and what should I do?
What you should do is stop posting useless posts. I can't find a single post in your post history that's worth reading, but you do have countless links to Twitter and Facebook.
Sometime I get posts deleted or moved on various boards, and I've learnt to live with it.
It happened to me recently, when I answered a question from a thread hijacker. I think in total I've had less than 0.2% of my posts deleted (it did happen a few times when I was a Newbie).