Indy, you don't ride a lot of long descents in Indy, do you? Could you have had your hands clenched slightly on the levers for a longer period of time than normal and your hands just tired? Common problem for folks with small hands.

I use hand exercisers that rock climbers use to strengthen my hands. Daily whacking away at the keyboard just doesn't do much for hand strength.

Just a thought as I think those brakes should be fine. Modern short reach dual pivot brakes should stop you with no problem. Only things I can think of otherwise, some of which you've covered: grease or water on rims, stretched cables and/or the point of engagement on the calipers needs adjusting (could be too wide).