Aftermarket proportioning valve leaking

[69heavychevy]

I replaced my old proportioning valve about 6 months ago with an aftermarket unit. The other day while driving I noticed my brake pedal was getting a little mushy. Popped the hood and saw brake fluid all over the frame crossbrace where the valve bolts too.
Leak was coming from the tiny whole that's on the fitting leading to the rear brakes.
My question is whether this was caused by abnormal pressure in my braking system, maybe some sort of restriction in the rear brakes. I did a complete overhaul on my front and rear brakes last year.
I'm also running hydroboost so I don't know if that could also be an issue?
Or maybe it just a defective unit? I bought from CPP if that makes a difference.