When collapsing or opening a tree view in Password Safe too quickly it will register as double clicking the last highlighted entry (usually the top entry).
By default this copies the password of the last highlighted entry into the clipboard. The worst case scenario is if "Do not remind me" has been selected for password copying, then this becomes a security risk, causing passwords to be silently copied to the clipboard.
Note that the passwords copied are not necessarily, and not usually part of the tree being collapsed or opened. It is whatever was last selected, or the top entry in the list.
To make the issue more easily visible: Open Options / Security and select "Confirm Item Copy to clipboard" (this is the default setting).
Now select any item. Then collapse/open any tree quickly. You should be prompted that a password is being copied to the clipboard.
XPSP2, PW Safe v 3.15.01 (2326) zip/no install. Application and database on network path (\).