Yea, it happens a lot. It's basically due to performance anxiety. I never used to stutter on hello before. But one of my friend was laughing at some other friend sounding like hell ye instead of hello. I started developing a fear of saying hello since then. No fault of my friends or anything. It wasn't targeted at me in any shape of form. But since then I started getting overly sensitive to how I said hello on the phone and it made me start stuttering on that word. Similarly with my name, sometimes when I want ppl to get it right and hear me properly I stutter at the start. But if I am not thinking of other things to say after my name. I can say it very fluently.