It took us a little while to realize what we had done. Once we did, we sent out the correction email as soon as we could. That's not an excuse, but I don't want it to feel like we were intentionally leaving people in the dark.

Sending the follow-up from a do-not-reply was also our mistake. Our default outbound address is do-not-reply, and we forgot to change it as we were drafting the correction. Please follow up to startupschool@ycombinator.com. :(