Check your belt and tyres. Some tread patterns can give off a similar sound to a crook bearing in very quiet moments.  Change / lower  the air pressures dramatically, go for a short careful ride  and see if it goes or whether the noise changes in pitch.  It costs nothing to eliminate it from the list.    Bizarre but true....

A mate only got 18K out of his, so not surprised.

I am a little curious about mine, only got 11000 on the clock, can hear the back ones when cornering at moderate speeds, I have a solid back wheel and I think this amplifies the noise ???

Any one else experienced this with solid rims? is it normal?

Well i don't know but at the start in 2001 i was a bit worried about the sealed ball bearings my FXD came with, but 10 years on and 80,000k all over the place even two up & big load on from Syd to North Qld. drag racing stunt riding and still original bearings, just have an out rigger bearing support on rear axl. maybe you all wash your bikes too much?

You won't be the first or the last to have bearings go at 16K. Mate had them go on his evo at 16K's also, so it's not a new thing, just the luck of the draw...Glad you found it anyway.