Customer Shipping Error?

Hi everyone. I have been an Amazon merchant for 16 years and today I encountered a first. A customer actually called me and told me he could not order one of my products because he received a red error message when trying to check out saying: “Sorry, your selected delivery location is beyond seller’s shipping coverage for this item. Please choose a different delivery location or purchase from another seller. “ I called seller support and looked in all of my shipping templates and nothing comes up as an exclusion to where I will ship. Does anyone have any idea why this happened and how it can be fixed? Just to test, I had my daughter order the product and had no problem at all. Thank you!