Renee,
Excuse the delay, I missed seeing your post here earlier. I read a paper several years ago referencing delayed fertilization in an African Rock, Python sebae, at the Rotterdam Zoo. Apparently she laid a clutch of eggs, of which about a third of them were fertile, three or four years after her last contact with a male. I have heard of a few other cases of delayed fertilization, but they are rare, especially in boids. I will see if I can dig any others up.

Kelly