The code for setting the remarketing cookie is installed on a page-by-page basis, so unless you checked every page you viewed on your previous visit you might not spot it.
I strongly agree with Chrispcritters that showing followup ads can backfire if it's overdone. Remarketing is like pepper on your pasta ... you need to keep a light hand about it or you'll ruin the recipe.
If our AdWords forum could achieve one thing over the next while, I wish it could be getting the message out to advertisers that they should be using tight frequency caps if they're using the remarketing feature.
Overdoing the followup ads is just shooting yourself in the foot.