HA HA...that's a great question. I laugh cause I have a couple of cowling screws missing on my plane and that's the first thing that a new student will catch on a pre-flight. Then they will proceed to leave a gas cap off...
150's have a type of cowling screw where you have to push it in and turn it to get that screw to lock. (I think fastener is a better word for them). What happens is the gismo inside, by the engine, gets out of alignment a bit and then they won't lock in place. I never got concerned if one or two don't lock and would have them fixed at the next inspection with a mechanic.
The vertical stabilizer ones are probably screws that hold a plastic or metal fairing on. There will be enough screws to hold it on, still, if one or two are missing.
A few missing screws is no big deal. I just tell the student, "good catch", and tell them not to worry about it.
Who is Dan? and what is he flying?
I think it's cool to have a mom around here. Maybe it will encourage people to be a little nicer and respectful.