André Comploi, a spokesman for the opera house, said in an email that it did not appear to be an intentional slight. He said that when Ms. Gheorghiu realized that Mr. Kaufmann would be repeating the aria, she returned to her dressing room. The confusion, he said, stemmed from the fact that there was no pause for applause after the encore, as there had been at the previous performance, and that apparently made Ms. Gheorghiu late for her entrance.

Representatives for Ms. Gheorghiu did not respond to an email seeking comment.

Ms. Gheorghiu has been accused of prima donna behavior in the past. She once balked at wearing a blond wig while singing the part of Micaela in Franco Zeffirelli’s production of Bizet’s “Carmen” during a Metropolitan Opera tour of Japan. That led Joseph Volpe, who was then the company’s general manager, to tell her that “the wig goes on, with or without you.”

In the next performance the wig went on without her. But for the following performances, she and the wig both appeared.