172, you are correct, however if you even get close to the issues involved, Danny cops another legal letter from Ryanair.
As for the non reporting of the slide bottle pressure to the Captain, there are a number of possible explanations, slovenly cabin crew, bad training, time pressure and so on.
However there is a possible behavioural reason - What if you tell the captain and the flight is delayed while the problem is fixed, and you subsequently get a bollocking from management for being a "smartarse"?
I've seen it done.