I don't think it's creeped out, more curiosity and maybe confused. Like a comment here said, stuttering isn't an actual common thing if we go by population size. Most people will never meet a stutterer to begin with, or someone with a severe/moderate one. Anyways, I think it just makes people question - "are they nervous? did they have an accident? should I finish the word for them?". One of my friends told me it helped for me to just be clear and ask them to not finish the sentence for me. Close friends now and they respect that request and I appreciate them for it.