It's odd purely because developers normally like to have a cooling off period between DLC. With Bioware it’s typically been around 2-3 months between DLC packs, though admittedly The Descent has kind of buggered up that pattern a bit. I suppose it could be that the descent was delayed for reasons unknown while the DLC the Edmonton team are working on is still on track and they don’t see any point in putting a release back. Regardless it'll be nice if we don't have to wait too long for the next one.
If they release the next DLC in November, it would be exactly 2 months between DLC releases. If it's a big, biiiig DLC, starting to promote it 2 months prior seems reasonable too. Releasing the next part of the story as a story DLC exactly a year after release is really fitting too.
Now I'm just talking myself into hopes that are going to be crushed, right...?