She was actually climbing a fair bit up a bookcase, unable to reach the topmost shelf and couldn't hear him. She was avoiding the red tagged things the best she could, trying to organize what was left into something that made sense.
There would have been no problem, except the tag had fallen off a particularly irritated looking mermaid statuette, and Ariadne picked it up to move to the shelf with the rest of the statuary. No tag meant no problem, right? The red tag was left on the shelf, too high up and out of sight.