In the course of Suzaku pipeline testing Lorella spotted a problem I introduced during the attempted speed-up of the fixwmp routine. Pixels with non-zero counts show up even within the part of the region which is supposed to be set to -1.
The particular case of Suzaku demonstrated a conceptual issue here. Those pixels showing up within the supposed excluded region are real events. What is happening is that the region is defined in sky coordinates but the WMAP is written in detector coordinates. I calculate a conversion to determine which WMAP pixels are within the image region however it is a time-averaged solution. In the pre-5.09 version the satellite attitude wobble results in some events being incorrectly excluded from the WMAP. It was these events that the 5.09 version actually included however they are potentially confusing to users.
The fix is checked in as v5.10.