brake light on, pedal soft, no leaks!

Had to slam on my brakes to avoid creaming a woman who slammed on hers to avoid a damn pigeon!!  Anyway something felt funny when I slammed them on.  Felt soft everytime after that.  Next time I started the truck the brake light is on and stays on. 
 
Looked around quickly (getting dark)  no leaks as far as I could see.  Fluid level good.  Brake pedal still soft but brakes seem to work fine just soft pedal and light is on.
 
Any hints?

master break cylinder or your booster

It may be that you smoked your brakes. Check to see if the rotor to see if they got messed up. I done it before with a rental car. Why are lights on highways?

I would guess booster, but it could be the master cylinder too.