INFERNO

I just bled all the brakes on my car today after pulling the engine. I have the Ls1 front conversion and stock rear LT1 brakes. The only wierd thing was that the brake fluid coming out of the front brakes has a silver metal color to it and also inside the master cylinder. The rear brakes were not bled enough yet to see if it is going to come out there too. The only thing I can think of since it is in the master, is that it is aluminum dust from the master being shot. Has anyone ever seen this?