Why are my pdfs locked when I add them to a specific folder?

When I find pdf files of articles I want to read on the web, I will usually add them to a folder in my dock which is watched by Mendeley. For some reason, the pdf becomes locked after I do this — i.e., it will say "Locked" to the right of the file name and page number when the file is open. However, when I open the information window about the file (or the folder it is in) from Finder, the "Locked" checkbox is unchecked.

So I have two questions:

• Why is the "Locked" checkbox in Finder unchecked, even though the file behaves as if it is in fact locked?
• Why is the file locked when added to this folder?