80ECLT

I have a 2016 silverado 5.3. I've had the truck since new. I have put about 80,000 miles on it and I have always heard a very slow clicking noise while idling. It clicks about one time every 3 seconds. Doesnt matter id the engine is hot or cold, its the same. Its mainly heard at a drive thru or when standing outside of the truck. Its not a fast clicking like injectors or vac pump. If I rev it just higher than idle the sound goes away. Has anyone else heard this sound or know whats causing it? I assume its normal because I haven't had any issues but Id like to know the source or at least and or confirm its a normal operating noise.