This is just the tip of the iceberg - for some time now, many international flights inbound to the U.S. have had a secondary screening of your carry-on bags at the gate. They won't let you take any liquids into the gate (beyond the 3 oz bottles) and go through your bags. They had this last month when I traveled from HKG to SFO. Other international flights not going to the U.S. did not have this screening. I think I remember an at-gate screening at Frankfurt as well, but my memory is fuzzy.
I just flew out of FRA to the states last month and they don't screen at the gate (or just before) anymore. But they have reconfigured terminal 1 so that all US-bound flights leave through section "Z", which used to be section "A". Everyone leaving through Z (since it's non EU/Schengen) gets a heavier screen than domestic flights leaving out of the other gates.
That(screening at the gate) has been going on forever though and most people (international travelers) are used to it by now. Most international flights to the US will have additional security screening for liquids/whatever since most destinations don't require the whole liquids/take shoes off/turn on your laptop crap.
Not saying it's right, just that it's been going on forever.
At least there were no X-rays or pat-downs...