Why would there be a floor tile in a wood shed?
Must be a really ritzy wood shed...................
What was the one doing, such that he was waiting for the axe to fall?
As the story continues,
The Gemara asks: What was he doing, that priest who noticed the misplaced tile? Rabbi Ḥelbo said: He was occupied with his axe, i.e., he was banging the floor with his axe. He thereby discovered an empty space under a tile, which he guessed was the opening of a tunnel. The school of Rabbi Yishmael taught: Two blemished priests were sorting wormy wood when the axe of one of them dropped and fell there, into the hole in the floor. Blemished priests were appointed to inspect the wood for worms, as these logs were unfit for use on the altar. And fire burst out and consumed that priest, so the exact location remains unknown.