Every time I flush my main floor toilet or my guest bath toilet on the second floor, and when my sprinkler system goes on my pipes make a moan sound, the second floor toilet moan is longer than the main floor, the sprinkler system also creates the moan when it first goes on (sprinkler system is on an auto timer). Do I have "air" in my lines and if so do I need to have the lines bled or will the air move on it's own? If it is not air, what could it be? I am afraid I may come home to a flood...

No, its not air and nothing is going to blow up. Probably a pipe or a valve washer that vibrates at certain volume and pressure. Could be in sprinkler control valve but could be anywhere.