BRAKE light under heavy acceleration

[spearfish25]

Last weekend I bled my brakes and swapped back to my summer tires. Twice since then I've noticed the red "BRAKE" light illuminate under WOT acceleration. The car responds and handles perfectly fine, and I have the brake fluid reservoir filled to midway between Min and Max. From what the owner's manual says, the "BRAKE" light comes on either when the parking brake is engaged or there is low brake fluid. I'm going to reluctantly open up another bottle of RBF600 to top up the reservoir (I wanted to leave it half-way empty for my pad change in two weeks).

I'm guessing this is just the fluid sloshing to the back of the reservoir under WOT acceleration 'g's'. Has anyone else noticed this issue or had the light come on with anything less than a completely full brake fluid reservoir?