4dpo... Is It possible to have early signs?!

So today I cried at greys anatomy. For those that have seen it, it wasn't even a sad episode, reasonably happy actually. I had tears but managed to hold off on the sobbing. I just read my children puff the magic dragon and had to stop because I was *literally* balling. what is wrong with me?!? I know Implantation wouldn't have happened yet but is it possible to have signs this early? I'm never this emotional!