Make sure the adjusters aren't swapped R-L....It happened to me once when I tore both brakes apart at the same time and then tossed all the parts into a pan to clean.

I reassembled them ok except I placed the right side adjuster screw assembly on the left and vice versa....Over a period of time they worked themself loose till finally a wheel cylinder blew out from too much travel.

The adjuster screw assemblies are thread backwards from each other, so it's important how the go back in.