This time of year, lawn service companies are clearing out irrigation systems "to put them to bed" before the ground freezes. Compressed air is blown into the pipes to force water out of the system. In this process, the spray heads may get stuck in the extended (raised) position. With a covering of newly fallen leaves, the stuck heads may not be visible. After the irrigation clean-out has been done, always check the various zones carefully before the first mulch mow!