What does it mean when a guy adds "lol" after a compliment when he texts you?

This guy I work with came to drop something off for me while I was at work when he came in I had my hair in a high pony tail and when he left he texted me "you look really cute in a pony tail lol" I'm wondering why he said "lol" at the end? Does that mean he wasn't being serious?
What does it mean when a guy adds "lol" after a compliment when he texts you?
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