PopUp Pro pops up too often when composing

WPMU

I have PopUp Pro and it looks great and works fine.

I have it set to appear after 180 seconds.

When I am in Edit Post and composing an article, I bounce back and forth between my work page and PREVIEW to see how things look. When I go to PREVIEW my PopUp pops up immediately and I have to tick the 'X' or the background four times to make the little booger go away so I can inspect my work on the front end!

Is this normal? Can I make it NOT pop up when I am working?

Thanks in advance.

NEAL