Inconsistent S.A.R.S. declaration?
 

Has anyone arriving into YVR noticed inconsistent S.A.R.S. assessment?

I flew into YVR on AS from LAX in the latter half of July and the big yellow health declaration forms were handed out. A few days later, arriving from MSP on NW, there were no forms (nor did customs ask for any). However on the same NW flight the next day, there were forms.