Tonks left the office about 5 minutes after Graylin, not wishing either of them to be followed or to cause suspicion that they might be meeting outside of the ministry to do nefarious deeds. It might be paranoia on her part, but she'd rather be paranoid than either of them lose their employment.
So she stepped into the restaurant a few minutes later, the buttons of her Auror's cloak already open against the hot summer air, a few fine beads of sweat on her forehead. She didn't take long in locating Graylin before heading over and settling across from the woman. "Wotcher, Grey. Sorry, didn't want to leave the same time. People might talk."