Very new to military vehicles, have a M923 I just use on the farm. It’s often started and driven short distance then shut down. I do drive on the road some. Started it half hour ago just to move it to flat ground to check diff fluid. It ran maybe 5 minutes. Shut it down, sitting in the truck answering a text and heard a gurgling sound. Coming from the air intake. Gurgling sound last about 2 seconds then about 6 seconds of nothing. Took fuel cap off & listened, not coming from there. Opened the air filter housing, dry inside, but could hear the gurgling. All air intake lines appear to be intact. So I assume the sound is coming from the engine. Anyone else ever had this happen? Anything to be concerned about? Thanks in advance for your assistance.