I just checked the spec. It seems to me that @cbeer was right. It certainly looks a bit odd, but what I understand it to be saying is that the subject of the membership relations implicit in the existence of an ldp:Container is the object of this triple (which in our case is the subject of the resource itself).

http://www.w3.org/TR/2012/WD-ldp-20121025/#ldpc-5_2_4

At least, that's how I read it. It's not as clear as might be liked, and it seems that in this case it is optional and only makes explicit the default assumption. I encourage you to triple-check @cbeer and my interpretation.