I guess I am only mildly surprised. Mikail Gorbachev repeatedly demonstrated, while in office, that he was very much an individual - someone willing to step outside traditional Soviet practice.
And, while in office, he formally granted tolerance for the Russian Orthodox Church, overturning 70 years of Soviet suppression.
Gorbachev is deeply patriotic, and Christianity (particularly Orthodox Christianity) is a strong tradition in Russian culture. In embracing his nation, he embraces its faith, too.