Seriously EVERY FLIGHT!

I'm not joking. Every flight I've been waiting for has made the following announcement:

We do apologise for the delay in boarding. This is due to the late arrival of your aircraft. It is currently being cleaned, refuelled and catered. Please note, we still expect an ontime departure.

What the heck? Was every flight out of the US delayed? Was there some huge headwind? What's going on?