I was recently promoted to manager. I have been noticing a pattern of subtle insubordination and passive aggression from one particular person on my staff, let's call him Mike.

Here's the background: Up until I promoted a few months ago, Mike and I were coworkers. In fact, he's been with the company a lot longer than I have and is about 15 years my senior.

Some of the behaviors I have noted are: (1) interacting with and addressing another employee as “boss” and attempting to get direction from them on assignments and not me - his manager, (2) greeting other staff in the morning and when leaving for the day.

I know that there is nothing directly in our company policy that your staff is supposed to greet you in the morning, etc. But I find Mike's behavior very rude and disrespectful and believe it is negatively affecting others on my staff and it undermines my leadership.

I had a discussion with Mike about his behavior of which he did not deny. While he has stopped calling the other employee "boss", he has continued to be blatantly disrespectful by continuing to check-in with one of my staff in the morning (who has no supervisory duties).

How do I handle this??