As your scene is a low contrast scene in the first place, you probably don't want to reduce the contrast further.

You indicate that you were metering on the middle grey values. With a low contrast scene, that means to me that with normal exposure, you won't come close to "using up" the highlight room that Tri-X gives you.

Two stops of extra exposure will just push everything up the curve, but as your scene was low contrast to start with, most likely there is room up there for your highlights (if you develop normally).

What film format were you shooting? I ask, because the increased exposure may increase the grain - not a great problem for LF, but of concern if you are shooting half-frame 35mm.

EDIT: I need to take typing lessons.