From my experience, the Gander controlers are doing the 020, and the Shanwick guys loosen up a bit and just do the 20. If you look at the N.A Orientation chart, it does say to use the full 020.
Now, from my experience, it really doesn't mater either way, as long as you are clear with your transmission! The controllers are smart and know what your saying whether you say 20 or 020.
As far as your comrades getting upset over that little detail, they need to get a life and probably need to be concentrating on other things that are a bit more important!