I don't know about a click, but it's pretty common for locks where the cam isn't touching the lock plate to open with gravity when the key is inserted. If you lock the coin door and you can "wiggle" the door then the cam isn't tight enough against the lock plate. Generally, you just need to bend the cam a bit to make contact with the lock plate. But, depending on the size (length) of the lock, you may need a different cam (i.e. an offset cam).