Ye Olde Title

Thats normal, they can go anywhere items can be placed.

Some go into areas that players can not see and can not get to.

Often the imp that spawn them will check when they are created.

Sometimes not and a few escape.

I tried talking to them nicely but they are a stubborn bunch who like to roam freely.

What Froggles is saying happened has nothing to do with the portal appearing in an inaccessible area. The portal appeared on one of the fake tiles in the back of Damor's shop. After using the portal, the fake tile is now gone, which exposes the skeleton.