Responses
dont bring logic into this
in the panel where Asley is waking up you see the sun rising so most likely they traveled to the dungeon at night, slept, and then entered at daybreak
Page 14: "We'll start exploring next morning."
So you are indeed correct.
Why are they traveling at night? Wouldn't you want to hit a dungeon during the day, when you are fairly well rested? Does the labyrinth only show up at night or something?