I am having an issue with an employee/former co-worker who is flat out ignoring me.
I work in a department in a college and for many years I worked as a student assistant. When I graduated I became a full-time employee and I became the supervisor to all the other student assistants. I have been in this position for a few months and at first everything seemed to be going well. All my former coworkers seemed to transition easily into accepting me as their supervisor.
However, as of a few weeks ago, I have noticed a drastic change in the behavior of one of my former coworkers/student assistant. At first I noticed that he was becoming rather distant towards me. I ignored the behavior because I believed that he may be stressed about school or that he may be having a bad day, and I thought that he has behaving this way to everyone. Now I have come to realize that this employee is only treating me this way and is now completely ignoring me. When he comes into the office, he does not say a thing to me. When he goes out for breaks or for any reason, he simply walks out right by me and doesn't say anything. I really started to notice that he was ignoring me when in the hallways he sees me and looks the other way to not talk to me.
I really don't know what I could have done to cause this behavior and I am having a really hard time trying to figure out how to deal with this because this is the last employee I ever expected to have a problem with. This employee has always been the complete opposite of a bad employee; he always does his work, he is always on time and he never complains. In addition, we have always gotten along very well. When I was his peer, I worked with him all the time and we were always talking to each other.
I am really having a hard time trying to figure out how to handle this situation. I don't know how to bring it up to him or if I should also involve my managers in this situation.
What is the best way to determine the issue at hand?
How can I resolve this issue and restore communication between us?