I have the same issue here in south florida. We had .5 inches of rain on Tuesday, 1.77 inches on Wednesday, 0 on Thursday (plenty of irrigation for at least 5 days) and now on Friday morning my system is back to watering cycle of 105%. I had suggested two months ago that the algorithm take into account a 3-7 day rolling average of the rainfall and allow us to set it at something like 1″ =0%. While it might be debatable, some turf in this area requires only 1″ of irrigation per week.
I love this system, but now that summer rains are here and we get upwards of 2=3″ in a given day (sometimes everyday, but many times it will be so scattered that my station will not get any for one day, but I don’t need to water the next day after 4″ of rain the previous two days.