I with those that say, it's fine.. Merge in turn is exactly what you should do.. as long as you do it considerately, which it sounds like you are..
I've found some places where big 'merge in turn' signs are put up with a nice diagram of the obvious, and this tends to stop people getting bent out of shape over it..
Still as idiotic as people are labelled for not using the Merge-in-turn, I see as many 'idiots' that don't understand Merge in turn and overtake cars that are merging even if their is only 20ft left, and pushing in.. causing heavy braking and it all backing up even more.. why people can't just let a nice 'flow' of merging occur I don't know..