Pet wont level.Follow

Hey guys,
I havent played my hunter in about 2 years so I'am a little rusty but I'am stuck on something I hope someone can explain to me.
After a lot of reading on various forums everyone seems to agree that the wolf is the pet of choice.
So I house my trusty old cat and go to Howling Fjord and pick myself up a nice level 70 wolf.
After playing for awhile I noticed he wasnt levelling although I was.
I have a fubar mod for my pet and it came up with " pet isnt gaining exp. because of level restrictions".
So my question is simple, what the hell does this mean?
Every other pet I've had in the past has levelled no problem so why now is this happening and what exactly is happening?
Level restrictions??
Do I just dump this wolf and get another?
But then maybe it will happen again?
There may be a really simple answer to this but being out of the loop for so long I have no idea what it is.
Thanks for any help :)

Thanks mate, always thought your pet levelled same rate as you but it has been quite awhile since I played.
Sort of like the other night when I went to the lexicon to my glyphs in, you dont have to anymore :)
And pets have talent trees, back in my day they didnt.....back then we had to walk to school on a dirt road with a hole in our shoes......lol
Thanks for the help.