I'd say yes....but depending.
Depends on if the beer clearly
exhibits a Saaz hop character...
And if it does, if entered into a competition would a qualified judge ding it based on the German Pilsner style guideline statement of "Hop flavor can range from low to high but should only be derived from German noble hops." I think a good judge should ding it. But that does not mean it can't be an awesome brew!
Just not technically to style.
So...if brewing for pure consumption...who cares? Push the envelope.
If brewing for competition, and you really want to be in the German Pilsner category, I'd say use only noble German hops. (Edit...unless as Jeff says, the hops fool the judges who take it to be merely a "similar to Saaz" German noble hop)
If already brewed, or you still want to do it with Saaz, there's always category 23.
Say...would you call a judge who dings a German pilsner for using Saaz hops a "Style Nazi"