Before you go guessing and (likely) talking yourself into hearing something that isn't there, I suggest you put the grills back on. Leave the room. Have someone go switch the placement of the speaker, or not (I'm assuming you haven't hung them yet).
Then, test them and see what you think. See if you can tell a difference between the two.
The fact that the damaged speaker is on a surround speaker should minimize directionality issues - to the extent they even exist - since they are designed to disperse, not focus, sound.
Most of all, enjoy!
