Nite Rider MiNewt X2 Dual LED lights

Recently upgraded my old Cateye HL 230s to a pair of these and am loving them except for one annoying little thing - the low level indicator switches the lamp/battery LEDs from blue to red with supposedly 15% of power remaining. Mine, however, swaps over with approx 45% power left. Anyone lse have this problem with the MiNewt range? Burn times remain as advertisd (1:45 at full power) so no issues there.