OK, a note to futre self, who won't remember this and to anyone who has ever asked the question: How do I center my Google Adsense ads in blogger when created with a gadget in a Blogger template?
1. Choose 'Design' tab.
2. Click 'Edit html'
3. Click check-box above code (expand widget templates)
4. Find the following code (ctrl-F and search for "adsense" until you find something similar):