SAN FRANCISCO -- Researchers are optimistic that two humpback whales are back in the ocean today after an unusual two-week stay in the Sacramento-San Joaquin River Delta. The whales, spotted late Tuesday off Tiburon, could have made it out of the Golden Gate any time after dark. Sighting reports this morning have not been confirmed and could be linked to other types of whales believed to be cruising through San Francisco Bay. "They could be anywhere," said Carol Singleton, spokeswoman for the state Office of Emergency Services. "The hope is that they're home and they're safe," Singleton said. "It would...