I figured the "bump" would be because of this:
HBO Possibly Coming to Netflix
This is obviously in the early stages, but would be pretty awesome if you ask me, and probably worth another $9.99 a month. The only question I have that you can't really glean from the info that is out there is whether you would have access to HBO shows right after they aired, or if they would only become available after a series is released on DVD. If you get it after it airs, then there is no doubt I get it; just cancel HBO and you save the money. Since I am sure they have thought of that, I imagine the details (when and if they get around to actually doing this) would sour the idea somewhat.