In Chapter 2 of Speaker, it says this
After all, the Bugger Wars were more than three thousand years ago; it was now the year 1948 SC, counting from the year the Starways Code was established, and Ender had destroyed the buggers in the year 1180 BSC.
A few chapters later, there is this conversation between him and Jane:
“How old am I?” he asked. “It has been 3081 years since you were born. But your subjective age is 36 years and 118 days.”
Now, 1180 + 1948 = 3128. How could he have been born less than 3128 years earlier?