For what this is worth: I've had a bit of experience with roller rockers in Husky singles. The TE570 clearances, for instance, were much greater than the TE610E. The latter was quiet until clearances opened up, whereupon it was as noisy as it's full-on cousin.

My point is that since the clearances in our bikes are even greater than a 570, it's not surprising that they are a bit rattly. I would be worried if mine went quiet! I set my clearances at about 7000km, as the inlets were too loose.