Nowadays there is always a minor passport check before you departure to/from US and to/from EU (especially Germany) and this minor passport check usually is at the gate. It is carried out by airline staff and/or a contracted securty firm.
They don't really ask that much questions, just check your passport, etc max ask how long are you planning to stay is it business or pleasure.

The immigration officer at the US border on the other hand will ask you all kinds of questions, and I mean all kinds.