It's become a tradition for former President Bill Clinton to stop in the kitchen at the National Constitution Center to thank the staff on his way out.

During Thursday night's Liberty Medal gala honoring Steven Spielberg, the former president -- who is the center's chairman -- did not disappoint.

Dinner service screeched to a halt when word filtered in that Clinton would take his short-rib dinner to go.

A grinning Spielberg (the medal dangling from his neck, Olympic-style) and wife Kate Capshaw were first to be ushered through the kitchen, the Secret Service clearing their way to a service elevator used by Max & Me, the in-house caterer.

Then came that familiar shock of white hair. Clinton slipped security to pose for photos and shake hands.