UTCTime reading back .5 fractional seconds .. is this correct? 3DMGQ7-GNSS/INS

[scotts11]

I’m reading back the UTCTime field from GNSS1 on a 3DMGQ7-GNSS/INS, and the time I get back looks correct, except that the seconds field has a half second fractional component to it (so this morning it was reading 14:54:13.500000). I thought the UTC timestamp should be the exact time of the rising edge of the 1PPS, which should be directly on the second rollover (so 14:54:13.00000). I know receiver puts out a 1PPS pulse that is 50% duty cycle, so this seems like something in the setup where the 1PPS falling edge or something is to be used, but I can’t find it anywhere. Am I correct in thinking that the UTCTime field should have a .0000 fractional component to it (or at least very close to it)? If so, how to do I correct the .5 fractional component I'm receiving.