It was something introduced almost from the outset of the first book and every piece of info we had said the DOs spies were rats and ravens. Now we get this nugget that says the TP can be used on basically any animal. Graendal can only channel a trickle of the TP and she still got it to work.. on a dove of all things (probably the most anti-DO animal out there). So it can't be that hard despite what she says. It's kind of a cop out IMO, especially since it was the key deciding factor for the whole scene.

Graendal didn't know what was coming until her magic birdie saw the access key glowing. She didn't lay an elaborate plot for Rand to find her secret lair. She pretty much got owned in the face but was saved by UFOs from Outer Space.