I've had issues with them on the back of my knees, but never the front. The back is from the bunched up material that creates redness and general malaise. I can't keep it stretched enough back there (even when it's stretched to the gills on the front).
I wonder why it's doing that to you??? Maybe you could put some kinesio tape just over the area that it's rubbing on that knee the next time? Funny how our bodies just find something to be cranky about for no apparent reason.