The CBP officer you saw in YVR did your customs inspection. (S)he may have deemed you low-risk with regards to customs, and (s)he may not have asked anything with regards to customs, but that still qualifies as a customs inspection. Your checked luggage was also checked by CBP in YVR. So you and your checked luggage
did go through US Customs at YVR, even though you may not have noticed it.
Through Preclearance, CBP Officers conduct the same immigration, customs, and agriculture inspections of international air travelers typically performed upon arrival in the United States before departure from foreign airports.
https://www.cbp.gov/border-security/...s/preclearance
Originally Posted by
junkDriver
SJC: it's a domestic flight from YVR, so no customs, of course.
YVR-SJC is not a domestic flight, even though you may have been discharged in a domestic terminal. If it was a domestic flight, you would have seen TSA instead of CBP before that flight.