Lightning bolts still create fire when hitting a lightning rod

The picture says it all. Tested the lightning rod (placed it down and changed weather) and the fourth lightning that hit set the block next to it on fire.

Important instant Edit: This picture was recreated. In the Original situation I had a Block of TNT next to the Lightning Rod. The Lightning hit, TNT got ignited and the block on the Opposite site of the TNT, next to the rod, got ignited by fire. Since the TNT exploded I wasn't able to create a screenshot fast enough