Yes like gojamadar said it's pretty normal. It's a level of hypnagogia. It will happen right before you drift off. You can hear your name being called out or jarbled or, random sentences. They can wake you up right before you drift off. It can actually be annoying at times. Some people get hypnagogic jerks. Where there body jerks right before falling asleep. And they may have that "falling feeling". Yours is quite similar to that, just a different response.