Remus was just a bit superstitious. It was nothing, really, except he always had to get out of bed the same side he got in, he always had to cross his fingers when making a wish, and he, every once in a while, had to turn thrice on the spot. There were other small, insignificant things he believed, like that black cats were bringers of bad luck (cats altogether were evil, but black cats were the worst). On 11.11.11, at 11:11, Remus quietly made a wish for Sirius to come home, because wishes made exactly at that time came true.