NPC Got You? Read This.
Seems some NPC's received better spell casting abilities and a lot of people are in a huff. My mate for one, heh. Read what Alan had to say, on the Developer's Corner, to help you understand better.
Just a tidbit to entice you...
"Keep in mind, though, that NPCs can be weak or strong for their ‘level’, and special NPCs can certainly be tougher or weaker than their /con might indicate. Having some of them cast higher level spells is just another tool, just like giving them procs or breath weapons or other innate abilities."