Pulsing in pipes in only one of my zones

I’ve had my sprinkler system for just under a month. I only have two zones and everything worked fine for a couple of weeks but now there’s what sounds like water pulsing through the pipe that leads out to the system. The pulsing is only while zone 2 is running and I haven’t noticed any issues with pressure or functionality of that zone. Nor does anything seem to be leaking, though I haven’t checked everything.