Sinclair is sensing a bit of tension here.

"I know you from somewhere," he says. If he can place her, he may have a better idea of how to go about the situation they're in right now. Her tone implicated that she knows him as well, but that doesn't surprise him. He's become something of a household name in recent years.

Her tone also implicated that perhaps she doesn't really like him. That doesn't particularly surprise him either.