Just did OLCI this morning for my YYZ->EWR->IAH flight on 3/7. Checkin went fine, but when I got the end, I was unable to print my boarding pass. Got a fairly bland screen with the following.

This is not a boarding pass.
You are checked-in, but we are unable to provide any
boarding passes for your itinerary via united.com.
Here is how to obtain your boarding pass(es).

Then it goes on to tell me to get my BP at the airport kiosk? Whats going on here, is this because I'm on the return leg of a flight that spanned integration day? Or because I'm flying out of a non-US Airport (YYZ)?

I have to check bags anyway, so its not a big inconvenience, but just something I've never seen before.