I have noticed the same pattern. There is something there like you said. My theroy is that the alogrithm that determines the drops regulats x amount of drops a day. In order to meet these drops and make sure everyone is happy it either drops alot of items early, and none later on, or if the drops are low it drops a bunch just before reset. I've said it many times, drops of any kind are not random, if we can find a pattern we should be able to correctly predict when medals/items drop.