Very faint, and the window continued to work properly, but I decided to spray
down into both lower sides of the inside and outside of the glass with the window
in the 'up' position using a silicone spray. Just directed the mist-like flow downward
into both sides where the rubber stripping meets the glass. Immediately noticed the
slight 'rubbing like' sound went away and has remained away for the day's driving.
Seems as if some part of the inner mechanism needed lubrication. Any excess 'clear'
silicone on the glass was easily removed with window cleaner and a paper towel.