It happened to me once a few months or so ago, I got 12 days off but I have a feeling it was an overlook on scheduling's behalf (not that I feel scheduling eeeever makes any mistakes). My favorite is I have 4 off, then 2 on, followed by 3 off. Those 2 on happen to be a weekend...way to spread out my days, like God forbid we have a weekend off here or there.