Why did my male friend drop his gaze to my midriff?

Okay so my guy friend who's never said to me (at least) that I'm attractive or anything knows that a lot of guys find me attractive but we have never commented on each others looks

So the other night I was hanging out with him and his mate I was on the couch and he was sitting on the chair watching TV

I stood up and was untying the jacket from around my waist I had a crop top on and I knew my midriff was exposed

At the corner of my eye I saw him watching me but I didn't look at him he watched me untie my jacket looked at my midriff/tummy

this is the second time I've noticed him do this the first time was like months ago he shows zero interest in me but gives me glances so guys what does that mean? Thanks

Why did my male friend drop his gaze to my midriff?
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