I think I can relate. Whenever I'm giving a talk or speaking publicly in general, my stutter is somehow greatly reduced. I think a lot of it has to do with confidence, and maybe an adrenaline rush that comes with that. Before I do any speaking events, I kinda say to myself "you're confident" and even though I actually may not be, I'm silly enough to believe that and stutter less. In casual conversations though, it's very hit or miss. Bad days and good days. It also depends on who I'm talking with and the context of the conversation. When I'm called out in these cases, I'm not terribly affected.