Deb, while I heartily agree with the chicks about not punishing yourself (which just usually leads to more off plan eating, at least for me), you do need to go back to Phase 1 (just until the cravings are gone, usually 3-5 days) if the pie had sugar.
While I've certainly fallen off the wagon a couple times, I find doing Phase 1 (frankly, doing it is less trouble than preparing for it, IMHO) prohibitive enough to force me away from those types of indulgences most of the time. Instead, I'll go home and make a sugar-free apple cranberry pie with a good fat WW crust and enjoy the heck out of it with no need for guilt or Phase 1.
I'm sure you'll find a balance that works for you.
If you don't think heading back to Phase 1 is necessary because you aren't experiencing any cravings, that's good. However, if you don't get cravings after a few bites of pie and you're looking to have a sugary indulgence every so often, SBD might not be the right plan for you. You might want to look into Weight Watchers or other plans. SBD seems to be most helpful for those of us who get the jitters after even one bite of pie.
Just a thought.