They have weighed my carry-on at SFO / LAX the last few times I have flown (in J or Y+) out of the US (always under weight until I get through duty free ).

I use a "wide body" rollerboard from Travel Pro (standard height, 2 inches wider), so it looks a bit conspicuous. Prior to this, never got weighed at HKG or anywhere in the US. Also, all these flights were completely sold out, so that may have had something to do with it.

Not sure if this is a recent trend or just west coast?