The puddling has to be caused by excess fat collecting in one spot. Perhaps, once the fat got hot and became more fluid, it collected in certain spots. I can't think of another explanation.
Once you've seasoned the skillet, the pan's pores are sealed and there is nowhere for the fat to go. Stop seasoning it and just cook with it.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan