Think of the upside, it was only 4 jaffa cakes as opposed to finishing off a whole pack (which I could do with ease) so I wouldn't worry about it, if nothing else, think of it as a little treat for being post-op and it was a one off thing.
Also congrats on getting to 9st12lbs, that's fantastic! Don't worry about the 10st1lbs because people fluctuate with how much water they drink and when they 'eat' the sachets.
You'll do brill tomorrow at weigh in, don't you worry. xxxx