Oo, this is the kind of drabble I love, where it's a tease for the much bigger picture. I could see Sarah Jane spending the next few weeks tracking down anything she coudl on "Miss Costello" and "Torchwood". Of course, Torchwood would like be on her case, too! Great tease, and very Sarah Jane-like!
Something about this piece is pure Sarah Jane. I don't know any why, but that's how it feels.