I consider it mild because sometimes I'm fluent, or I manage to hide it very well by saying certain words instead of others. But other times it's harder and people can tell. I don't really repeat syllables, it's more like a long silence while, as previously mentioned, I transfer all the tension onto my eyes, causing them to be wide open; although in those cases I tend to keep to myself and speak only when necessary or when I'm confident enough. Still, I think it's important not to feel discouraged by one's own stutter in instances like the one you describe. There's much more to us than the way we speak, and those who love and appreciate us know it as well :)