The idea of humorous vampires with principles is very entertaining indeed and not something you stumble upon often. Throw a midget into the mix and you have an even stranger and rarer combination. Clever thinking. It works perfectly as a short story, but we got to know Tomas so well in so little time that I personally wouldn't mind following him on his adventures in a short novel too.
I must admit, the summary didn't quite do it for me - until after reading the story. Then I realized just how funny and well it fit. Kind of like a blooper, an extra treat you get for finishing the story.
The story had a twist, which I liked, but I think you could easily have screwed around with us a bit more to give it that extra surprise factor.
So all in all, really great story. Though had I been the one to categorize it, I'd call this comedy rather than a horror story... Unless of course you're a pedophile ;)
Keep up the good work and good luck with the contest :D