My suspicion is the paycheck immediately following the missed sequences still reflected the credit for the sequence. Since you missed the sequence, your base pay would have been reduced by those hours and they would have subtracted those hours from the second subsequent pay check. Finally, they would have paid you for the sick time on the last check of the following month. This is how it works comping out of training when per diem is paid current to the regular one month arrears. I suspect sick and monthly vacation would be the same.