We've started noticing some strange cases after doing the 1.5.7 upgrade, this store now over 15 years of zencart use.

So, a customer creates an account in the same country as the store (UK).
customer goes away.
customer comes back at later date to purchase.
goes through checkout process, selects shipping option, then selects paypal option on the payments page.
goes to paypal - but his "eligible" address is in Spain, so it defaults to use that as shipping address (for 'seller protection' - whatever thats worth)
The cart automatically removes the tax correctly, but the shipping pricing option remains that for UK, not for international.

It never used to do this, it used to change the shipping option to the new address too.
the setting in the paypal express module is (and always has been) to 'select cheapest automatically'.
the address setting is to ship to confirmed address.

Shipping module is Conor's CEON Adv shipper. Maybe its not getting notified of shipping address change?

Ideas?