Hello everybody,
I am getting ready to send my queries out for my recently finished novel. In the meantime, I'm thinking about submitting a chapter to an anthology. (I seem to remember George RR Martin submitted just Dany's story as a novella before Game of Thrones came out.)

The anthology states: By submitting your horror short fiction work to Dark Moon Books, you are assigning Dark Moon Books exclusive First World Rights for both print and electronic versions for a period of six months after publication. After that time period, you are free to resell your story as a reprint as long as first publication information is included. You keep all other rights including the original copyright.

Assuming they published my story, what would the impact be of mentioning in a query that an excerpt had already been published? And would it interfere with the rights at all? In short, is this an advisable course of action?