The gap, if it exists, is very slight - sometimes it's enough, sometimes not. I had to remove a tiny amount on one, and a little bit more on the other. Try your locos a few times in both directions through your shortest left- and right-handed points and the tightest curves - if they survive, you should be OK.
You only need to shave the very outside corner of the coupling socket, nothing that will affect the location dimensions, should you ever wish to replace the coupling later on.