Exclusive Details

Melania Trump had a lunch date with her son and inadvertently created a huge scene at a popular NYC restaurant, or more simply ... she got a taste of her new life.

Melania and Barron hit up Serafina, but not before Secret Service showed up to sweep the place and warn the restaurant "she's coming." We're told restaurant staffers weren't immediately clear about who "she" was.

Moments later, the future First Lady showed up with Barron and their Secret Service detail. We're told an area was cleared around their table for some space from other patrons ... who were all wanded with metal detectors.