Brenda,
Unfortunatly, in the breed standard, it leaves open, a few things, yes it states 28 inches in my NCA member book from 1992, it also states this, wich can be taken to the extreme by some:
"Average Height for dogs (note they say AVERAGE) is 28 inches and weight for adult dogs ranges from 130 - 150 pounds, it also goes on to state, "Large size is desirable, but never at the expense of balance, structure, and correct gait." many out there are not aware of what the correct gait is.
therefore this can be misinterpreted by many who breed the 170-180 pound dogs.
They can easily state, that their dog moves like a dream, usually stated by first time newf owners, who have no experience (no offense intended)
the best way to prove it, is to show, even if on a limited basis, i am on a very limited basis, we still win points the few times we were out.
i used to sit ringside studying many many breeds how they move and tested myself and some friends comparing what we chose to what the judge placed.
anyway, yes the standard is a bit vague, wich does put our newfs in a bit of danger.