Front brakes popping when wet out

[robh2]

Picked up my 2500hd, 4x4, 6.0 auto last week and I drove it in the rain today, and noticed when I push on the brakes, the front end makes a popping noise. It stops after the brakes start to work and then when I let off it makes some noise again then again when I push the brake. Anyone else have this problem? It might do it when its dry out but this is the first time I had the radio turned down while driving and braking.

 

Thanks.

 

Robert