Interesting, I just noticed it also this week in an East Coast swing. When I checked, it looks like the last routine one I had received was on the domestic portion of a international return on March 15. None of the ones earlier this week showed up. I thought perhaps my cell provider had changed something, but test messages (both directly and thru United) showed up. Tried to reregister, and wound up with 2 notices, so deleted one, and then this morning on the return from JFK both the upgrade notice and the flight notice turned up, although not much ahead of time.