Not doubting that you're real lean, I know people like that too. It's just that most of the time a caliper measurement is not correct. The lesser points taken for the measurement, the more room for error. I don't even like a 7 point test; you can eyeball it and guess closer than that will probably give you. Different people hold body fat more in different areas, so the less taken into consideration, the more room for an incorrect, actual measurement.
Not sure about you but I'm one who'd rather be dead on when saying something rather than go off an inaccurate measurement. Again, the measurement was most assuredly taken properly, BUT the calculation itself is quite error-proof.
With that said...as I stated already, 9% is considered ripped by most people who aren't a bodybuilder. 7% would be a big step down from 9 (because it's already so low, the smallest adjustments make more of a change in appearance) and so on. Now with THAT said, the difference between 5% and 7% is much larger a gap than say 15% and 13% (which is why we're making such a big fuss
)
At 5% and under with decently added size from the gym, you should look nearly like an anatomy chart.