SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I just bought a seven year old house with a builder installed Rain Bird sprnkler system. It was a foreclosure and had been let go, so I had to plant a new sod lawn. I sorted out the Rain Bird ESP-6tm sprinkler system controls and started using them. I set the controls on "custom" and programmed the sprinklers for Monday, Wednesday, Friday and Sunday. The durations for stations 2 and 3 were set for 15 min. The other four stations were set at 00. The first start time was 5:30am and the second start time was 5:30pm. The sprinklers worked well until yesterday. Thursday was an OFF day but around 10:30 last evening the sprinklers fired up. I checked the controller this morning and the day, time, selected days, durations and start times are still set as I indicated. What would cause the thing to go off at 10:30pm? Help.