I do things like skip small words all the time when I read out loud to my kids
I get going and am reading at a good speed and it's just a thing that happens. My guess is that there's a good chance it won't happen for him when he reads for a teacher because he's going to just naturally read a bit slower and with more attention - simply because of the situation and being aware of having the teacher listen.
It's also been a while for us, but I thought that when my kids were being tested for reading levels at school, comprehension counted as much (if not more) than actual words read aloud.
Best wishes,
polarbear
