I would be nervous too! Honestly I don't think there is anything anyone can say that will make you feel better. All it takes is a couple of yeast cells that went dormant waking up and starting to chomp again. If one out of 5, maybe 2 or 3 out of 12? How many did you bottle? If it were me, as crazy worrier that I am, I would not sleep well until I pulled all the corks to check. Worst case you'll get to drink a couple fizzy grand cru, best case you just need to recork right away.
I know a lot of folks say as long as you put in the sorbate you are good to bottle, but I always wait a week or 2 post sorbate before I add sugar, and then again a couple more weeks before bottling. Remember I said I was a worrier. OK I'm paranoid too.
Pam in cinti