Who knows why cats do things ? One of mine brings me pine cones....no rhyme or reason....he just will bring pine cones home sometimes. He also likes to lay in the bathroom sink when I am in the bathroom. I gave up trying to figger them out....just glad I am not seen as a toy or food to them.
It's one place they know you go to on a regular basis, so they corner you there, in order to get some warm fuzzies, i.e., petting, scritching, and other personal attention. My guys do the same thing. By the way, when a cat bunts you with his head (you know, when she bumps you or rubs) it's her way of saying, "I love you".