Deja Vu

I had completely forgotten something that started occurring towards the end of my pregnancy with Skyler. Every once and a while, when he would move, I could hear a distinct 'popping' sound. Like a little click of a joint, or something like that. I think I would have forgotten that piece of information forever if it hadn't happened again today when Mason was doing his morning calisthenics. The very same sound. So many things have been different between these two pregnancies, but this little piece of identical really ties them together. Any one else ever have one of these moments?