Does iTunes Lock Imported Files?

I noticed that the CDs that I import as MP3s into iTunes have a little padlock in the bottom left corner when I view the actual imported MP3s in Finder (in the iTunes Media folder). I noticed because I wasn't able to change the ID3 tag info in iTunes (the fields were greyed out).

Is this default, is there a way to turn off this feature? I know I can manually unlock the file through Finder, but would rather not have to.