I've had the same, but then I also had it last month on CD 18,19,20 then 28,29 (being a 29 day cycle and pos opk on CD 16)
This time I've had it CD 18,19,20 and 24 (pos opk on CD15) so this week is a little out of the ordinary compared to last cycle, as I'm not due until Sunday and was looking to get increased cm on Saturday!
Wierd! Next month I am definitely temping!