That also happened when Benedict after being elected appeared in the balcony and released a dove. What appeared then was a gull. Matter of fact I posted a comment about it.
A lightning bolt strikes the top of the Vatican’s St Peter’s Basilica, just hours after Pope Benedict XVI announced his surprise resignation on Monday.
http://www.theguardian.com/world/video/2013/feb/12/lightning-vatican-peter-basilica-video