There is always someone who is going to be close to a cut-off line - be it height, age, or even how many weeks pregnant you may be. And there are always going to be people who are going to try to slide by - after all, "what difference does an inch, a month, a week, really make?"
But if it didn't make any difference, there would not be any cut-off. Just because you, or others, have ignored certain rules without any consequences (or have found a way to circumvent them without being caught) doesn't mean that will always be the case. The fact that others have gotten away with ignoring the rules doesn't mean that you can or should. As Jiminy Cricket would say, "Always let your conscience be your guide." Not anyone else.