Hi Tim, welcome to the site and sorry no-one responded to your email.
I found this email searching the site - I happen to have both issues on my 94 D90 - my Brake Pressure Reducing Valve is leaking and my brake pedal moves side to side, although I think the pedal has done this as long as I have owned it (over 10 years). The pedal pivots on brass bushes and they must be worn. I'm not sure if it's anything to be concerned about, or just annoying
But regarding the valve, has anyone taken one apart to see if it's just an o-ring or something, or is it non-serviceable?
Here is a picture of mine: