I know what you are talking about. I felt it on the ducati 959 panigale. My F3 sometimes has it but it'll go away pretty much every time I do a bleed of the master cylinder.
I just live with it but the F3 is consistent. It will grab at a low point but always do that until the bleed. The panigale I could pump it and sometimes it would grab at more of an open position and others at a more closed angle.
I think it is air but it isn't bad really.
Do a bleed at the master and see if it helps. The abs bleed is a bit of a pain due to location and general messiness so do that as a last resort.