You should be able to reposition the grooved piece that serves as a guide to the cable around the BB. Unscrew it and slide it back toward the droppouts until the cable no longer touches the frame (this part usually has a two/three mm play. It looks to me also it is not entirely in straight line for the rear derailleur cable (good pics, what kind of camera do you use ?)
I noticed this on my bike also. I don't think it is good to let your front derailleur cable have any kind of friction with the frame.
If this does not work, get a piece of derailleur cable housing (thin type) and get the cable through it along the line where the friction occures.