If I were to guess, she was either calling someone, or was just waiting for something and read a book or listened to the radio. This probably covers 90% of all possibilities, leaving the remaining 10% to bird-watching, or to taking some aspirin, or to checking the map, or to some other, not exceptionally likely, activity.
Hmm.. But why would any of that cause somebody enough concern to call the cops and report a “suspicious person”?