Night Elf Mages are known as "The Highborn." These are the Night Elves who followed Queen Azshara when they discovered Magic from the Well of Eternity. Through events, the Burning Legion tried to enter the world through the Well of Eternity and eventually caused the first Shattering of Azeroth. Magic was then banned from being used within Night Elf Society.
Some Night Elves tried to use Magic anyways and were then Exiled from Night Elf Society... Some of them continued to be Highborn, while others went off and became what we know now as Blood Elves. So yes, Night Elf Mages make perfect Sense.