Deximo did ask Una what she was doing there, dressed like that.

"Iris tell me to pose more for you," she replied, "She looking for Randi now."

Deximo tells me that at that point, he pretended he was out of film and went off to find Randi himself. After all, he was supposed to be spending the night in her dormroom and the last ferry had indeed left several minutes earlier...

Una did seem somewhat relieved. She apparently had her own plans for the evening, as well.