One sock? REALLY?

I am a fairly intelligent woman.  I know assigning logic or motive to a dogs behavior is unreasonable. That being said. . . 

What the heck is this dog doing?  During the night Lady removes one of my socks and hides it.  Found it.  Put it back on. Went back to sleep.

Four hours later the same sock is gone again.

Where is my sock DOG!!

There seems to be some kind of reason behind this, but I can't figure it out.  Maybe she just doesn't like a sock on her pillow?