quick look pops up in wrong screen

I have 9 virtual screens enabled in Spaces and when I activate quick look on items located in the desktop it happens frequently that the pop-up preview window opens in another screen, for instance I choose to quick look a photo while I am in space 5 and the preview is shown in space 3 or space 6.

Is anybody else encountering this weird behavior?

I am on Snow Leopard 10.6.8, but it has always happened since I installed the first version of the O/S.

Thanks

Flavio