What does it mean when a guy stutters around you when you hang out alone but not when we are at work?

I noticed this guy stuttered a lot when he first met me and when we hung out alone for the first time. But when we are at work he doesn’t stutter when he talks to me. He talks very normal. That’s something I noticed. Why would there be a difference? I will say when we did hang out he told me he was nervous but for what. We literally talk all the time at work with no problem. He literally has no problem coming up initiating the conversation because he does most of the time tbh.
What does it mean when a guy stutters around you when you hang out alone but not when we are at work?
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