We all do it from time to time -- and are often annoyed when others do it. In a new position, we talk about "how it was done (better) where I was before". DON'T DO IT. Until you are well established and understand WHY things are done the way they are in your new position, don't talk about the way it was done in your previous position. People don't see it as helpful. At best they see it as mildly annoying. Avoid it.