On a side note...I thought of this before but these panels are helping to prove my suspicions....I think Zoro is purposely avoiding stairs subconsciously? I can't remember if he has gone up any stairs but I joked about Zoro having "PTSD (Post Stair Traumatic Disorder) after what happened to Kuina and doesn't trust stairs and avoids them without revealing why openly. And thus it contributes to his "getting lost" gag but in a tragic way ironically? A sort of bittersweet revelation?
Fun theory, though.