Brake fluid leaking around bleed screw threads when screw loosened

[dogguy]

I was recently using my Power Bleeder to flush the braking system on our '85 300CD-T (123.153) and got to wondering:

Is it typical and the-way-things-are-supposed-to-be that upon loosening a brake bleed screw, that fluid leaks from around the screw threads?

I am loosening the screw just a bit - enough to get a small stream that puts out 8 oz. of fluid in like, say, 2-3 minutes. Hardly loose at all.

This leaking from around the threads happens on the ATE calipers in the rear and the Bendix (ack!) calipers in the front.

Anyone have any insight on whether this leaking is right or not and if not, what to do about it?

Thanks-