QPrintDialog position

QPrintDialog's exec() works different than QDialog's exec(). The print dialog position is not centered on screen, however it has a parent.

eg:
QPrintDialog dialog( printer.get(), this );
continuePrint = dialog.exec() == QDialog::Accepted;
--> not centered (appears on the top left corner)

but if I use here this:
QDialog tmp(this);
tmp.exec();
it's centered...

It's a mistake by me, or a bug?