In this instance it really is totally "normal" in these bikes with a hydraulic clutch. Called "neutral rollover" or something like that. Can't give you the specifics why though. Others maybe can. I have a '12 FLHXSE3 and it does it but I no longer notice it since I no longer concern myself with it. I say ride on.
Per H-D the noise is caused by the stack up of tolerances in the first gear pair. Those are still straight cut gears, not helical. I'm not convinced that is really the full story, but Harley rarely tells us the real story. It probably also has to do with the poor design, execution, and tolerance of the trans shaft bearings in the trap door. They supposedly reduced the radial runout tolerance for those bearings for 2012; obviously with continuing complaints on 2012 models they still haven't solved the issue.
Calling stuff normal is what Harley does best. While it may be
normal to them, it's not necessarily
acceptable to a lot of customers. Other companies I'm familiar with have taken action when surveys and other feedback show significant dissatisfaction with a particular item, and even though the item was technically "in spec" they fixed it in future models. That's what companies in highly competitive markets do to improve customer satisfaction. If you're in a market like Harley, they obviously don't think they have any competition and thus don't have to respond to customer dissatisfaction. The fact that so many Harley owners bitch and moan about all the quality issues and lousy customer service, but go right back and buy another one, tends to allow them to get away with their cavalier attitude.
Anyhow, to make a long story short, Harley will not authorize a dealer to make repair attempts to correct the neutral rattle. You will need to learn to cope with it. Most of us Harley riders have learned to cope with much worse stuff.
Jerry