single-click registers *two* clicks

I just bought a new 12" PowerBook, and I'm noticing that sometimes when I click, two clicks are registered. This is merely annoying when I cmd-click on a link in Safari (two tabs with identical web pages get created). However, if I delete an email by clicking on the Delete button, I end-up sometimes deleting two emails instead of one. Not cool. Anyone else ever notice this?
(By the way, I do not use an external mouse. Also, double-click speed under trackpad keyboard&mouse preferences seems to have nothing to do with it.)