Dear Mary: Can I ask my vegan friend to buy eggs and bacon when I stay with her?

Q. The other day a dear friend rang from her car with all the time in the world to burn as she crawled along the Hammersmith flyover. I was at my desk working, as I politely told her. Now she has described me as unfriendly. How can one appropriately deal with the frequent asymmetry on the leisure-work spectrum of two interlocutors as a result of the use of the mobile when walking or in a car or train?
— O.R.,