When an E-4 calls me "hey" or "hey man" knowing that I am an officer, should I bother to correct him?

I'd probably address him by his rank and tell him, "I address you by your rank because I respect the work you put into achieving it. And I'd be negligent if I didn't tell you it's in your best interest to treat officers (or NCOs) with equal respect."

I did that to an officer. once But, I said hey and we knew each other pretty well. You talking about a disappointed look. And then I walked up to him and apologized and addressed him appropriately

Yes, you should correct him! You are an officer 24/7 as he is an enlisted 24/7 Respect must be shown at all times
Maybe I'm "old" school but even when I ran into an officer that I knew I address them by sir or by their rank

I don't know what Army standards are concerning his disrespecting you and your Rank but, in the Corps, he would be corrected on the spot! lol. I as a Lance Corporal from 3/5 had to pull aside a Sgt. when I was F.A.P.'d to Base Motors when he was doing something unbecoming of his Rank in front of Junor Marines. Later he thanked me for it.

NOTE: I'm sure Army Infantry Units run the same way Marine Grunt Units do when it comes to Respecting Rank. Meaning they would straighten that E-4 or any other Soldier out.

Sir,
COA #1: I would explain the Rank Structure of the United State Army to the SPC in the presence of his Team Leader, Squad Leader, Platoon Sergeant and Platoon Leader. Once that occurs, I suspect that the NCOs will provide remedial training to the SPC in Military Customs and Courtesies.

COA #2: A friendly conversation with the SPC's First Sergeant could result in the SPC getting the attention/mentorship/training that he/she requires. Based on my military experience, First Sergeants will NOT tolerate a soldier's ... disrespect to an Officer or NCO. Nobody wants to 'piss off' the First Sergeant, the consequences could be unpleasant.

COA #3: Ignore it, drive on and establish an unprecedent standard of dis-behavior for others to follow. I don't think we want that, but ...

CPT Railey, thanks for the laugh. You are kidding, yes? It brought back a sweet memory of mine while I was a CW3 with a WO1 walking alongside me to the left as he was supposed to. An Enlisted Soldier was "casually" walking by and did not render the proper military courtesy. My WO1 went in on him hard like a Drill Sergeant. He did the right thing because I would've lit my WO1 like a Christmas tree because he was closer to being an NCO than a Chief. Out of sheer respect, some of my former Senior NCO's to include Sergeants Majors and Warrant Officers still call me Chief and they don't even have to. How could or would you allow an active duty Soldier not to address you as Sir when they know you're an Officer?

Definitely correct him.

The fact that you have to ask is disconcerting.

I most definitely would correct him but in a nice but understandable way.

Are you serious???? It’s not about your rank, its about requirements to be ready to fight and win our nation’s wars. If this is a hard question for you…. Please resign your commission TODAY!!!! You are NOT officer material! I had two LtCdr Naval aviators try to walk past me without saluting at Norfolk Naval Station, when asked they said that they could not see my rank insignia on my beret…. We did about 350 push ups until they could not push themselves off the ground. Set the Standard,”lead, follow, or get the hell out of the way!” It isn’t about you, it’s about the good of the service and building the discipline necessary for troops to survive.