Are stumble-upon-dungeons a one time opportunity?

[smuglapse]

In beta18 I had just completed the Maze (correction: Sand Pit) and was going to Angolwen to sell my loot, when a message popped up about a scary dungeon with muffled cries. I had the choice to enter or leave, and not wanting to miss my opportunity I chose to dive in. If I knew I could skip it and come back I would have so that I can make room for new loot. In this instance it may have saved my character, as well.

I was done in by an Elven Blood Mage that used Weakening making my loot unbearably heavy. I could throw traps at him, but I couldn't force him to walk in them, so my choices were to unload goods one by one while he blasted me with blight and other spells, or take a chance with teleportation. I was only a few hits away from death and chose the latter, only to end up in a huge cluster of these cultists who blasted my rogue into the next life: Character Page

Would I have been able to revisit this dungeon if I had ignored those muffled cries for the time being?

Also, this dungeon seemed quite a lot harder than the other random one I found (the Trapped! quest). Does the game take your level into account when it offers you these, or are they just at random spots on the map?

[madmonk]

The game does take your level into account.

The trapped quest is a one-off opportunity and can be completed by a relatively low-level PC (4+) fairly easily.

The other one I can't remember about since I go in every time...