My error, I think - got to find that Nichia chart again, increase current in any LED should add output at shorter wavelength! You're right bluer with more current.
later - I was remembering the chart wrong, even though I know which way the peak should shift!
1 mA is 510 nm
5 mA is 507 nm
10 mA is 505 nm
30 mA is 501 nm
even later - Because of where these are intended to go Nichia has also figured color shift of running with plusating DC (full wave rectified AC). It looks to be about 4 nm toward the blue. That would be 2 mA to keep the color peak at 505 nm!