That 139 Kt is at FLIGHT LEVEL, not at sea level; that's still a solid 4, probably around 145 MPH or so, not quite a 5.
Looking at the visible satellite, I think Frances is feeling a slight effect from the northerly winds ver the central and northern Bahamas.
Link: http://www.ssd.noaa.gov/PS/TROP/DATA/RT/float-vis-loop.html