Someone who works in Democratic politics floated this theory my way last night, and it makes sense: Gregoire is looking at the medical marijuana bill with an eye toward future confirmation hearings—her possible future confirmation hearings.
Think about it. No one expects Gregoire to run for governor again. Everyone knows she's been brought up as a possible Team Obama member in the past. And, obviously, having signed a medical pot bill that can be seen as flouting federal law would be a liability during any upcoming D.C. confirmation process.
So it's worth asking: In Gregoire's political calculus, is it the Washington State medical marijuana bill vs. her future in Washington, D.C.?