I'll join the crowd--searches are very common but they're only aimed at whatever the wand finds, they aren't TSA gropes. Chinese security seems to work with the understanding that it's almost certainly nothing and they are simply confirming this, rather than the TSA-style gotcha.

(If anything I would say they're too quick to clear things. My wife set off a nuke detector and they cleared her quickly without seeing the card from the lab or doing anything to confirm she was hot rather than anything she was carrying.)