I've been wondering about the shelf life of that "loan", and while it's reasonable to surmise it was early batches with a limited life, it doesn't look like that article is specifically describing the US shipment as near-expiration.
But: a bigger problem is that most came from the troubled Emergent Biosolutions plant, never FDA-certified, where all of its J&J production has been held back from US use:
I'm under the impression that the US has been sending its AZ doses to Canada and Mexico since mid-March: https://www.theguardian.com/world/2021/mar/18/us-astrazeneca...