Second chance at icloud upload? If photos are not automatically uploaded to icloud due to some transient error (environmental or otherwise), does icloud try again? Or do they get just one shot and if that doesn't work, they don't upload?

The Apple Genius just told me that they get just one shot and if that doesn't work, I have to do it manually.
If the photos are unable to be uploaded to Photo Stream, they will be attempted to be uploaded again at the next available time. There's no 'one chance'—it'll try as many times as necessary until it succeeds or other circumstances make it not necessary to upload them.