Was it overconfidence?

Was there overconfidence in Sarah Sessom's ability to cloak her home as a sort of shield to hide Bella from her pursuers? Was it a matter of underestimating The Arm's – and thus Dominic Black's – ability to use new technology to see THROUGH the disguise? And did it even matter now…?

Keith knew there was no way it could happen forever and that eventually that cloak would not be there, so he didn't really know what the hell the plan ...