Why was he doing this while talking to me?

My co worker told me that I should put my hair up because he didn’t want me to get into trouble for it being down.

When we were talking about it, for about 5-10 seconds he had his eyes fixed/was gazing onto the LEFT side of my apron/upper part of my thigh where the apron ends and my black long slacks show. (noting, both on my left side) He was directly in front of me but he did it with his right eye and side eyed me. He never made eye contact with my face while he had his gaze fixed onto my apron/upper leg.

Why? What he was looking at me?
Why was he doing this while talking to me?
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