I've been told it's really common for people who stutter. It's definitely hit or miss for me. My SLP told me it's probably a combination of the pressure you put on yourself to respond effortlessly, your inability to truly substitute something else and your assumption that the person you're speaking to expects you to respond immediately. I feel like I want to say this can all be wrapped up under the term 'propositionality' when it comes to saying your name. Probably wrong on that so don't quote me.