Rattled
Matty and Jesse were rattled by what they had seen. The silence and the sensation of being cut off from the world were taking a toll on their senses. This environment was ripe for their imaginations to run wild, so they had to try to keep them in check.
Was there someone down there in the dark with them, or had it been a trick of the light? Either way, they had to get out. The noxious gases that could be in the corridors also posed a threat.