Brakes grab when wet

Have an 09 2.7 standard cab. put new front brakes, pads and rotors. pads are oem, rotors are aftermarket. Work good most of the time until it rains or gets washed 0r on an especially damp day then they get grabby. Any ideas why?

 

My experience: Drive in rain or wash truck. Put in garage overnight WET! Next day initially 'grabby' brakes! It's the ROTORS rusting! OEM rotors not so noticeable, after-market MORE SO!

 

Did you bed them when you finished?

 

Normal. Flash rust.

That being said, make sure that your pads are correctly installed. What I mean is that the pads should be lightly contacting the rotor when the pedal is not depressed. If there is a huge multi millimeter gap then something is not right.