When the motion detector detects motion in it's field of view, even when the system is disarmed, an exclamation point appears next to the motion detector icon on the touchscreen. This symbol will stay there for ten minutes after motion in front of the detector has ceased. This is to simply let you know that motion has been detected recently, it is an indication that the motion detectors are working properly. You will probably see this quite often while you are at home. Even if this symbol is present on the screen, you can still arm your system.