Why does Dobby accompany Lucius Malfoy to Dumbledore's office in the chamber of secrets?

Harry and Dumbledore are in Dumbledore's office after Harry has defeated the Basilik in the Chamber of Secrets, when Lucicus Malfoy bursts in accompanied by Dobby. Is there an explanation as to why Dobby is with Lucius at this time? It just seems a bit strange that Dobby is with Lucius at this time, when on other occasions in the book Dobby isn't with him.