Does my Monstera have a fungal infection? Browning on underside

Hi all! I'm a new plant owner and recently bought a Monstera a few days ago. I've since noticed some browning on the underside of one of the leaves. I've also noticed some browning on the plant stem. I'm wondering if this is a fungal infection or something else I should be worried about? I'm a beginner to identifying pests and issues, so any help would be greatly appreciated. Thank you!!

Note: I should say that the leaf that has the browning underneath is also slightly damp/soft to touch as opposed to the other leafs.