Whitney Houston might want to think about a move to Arizona. While in Phoenix filming Waiting to Exhale, based on Terry McMillan's best-selling novel, Houston seemed to have no need for a bodyguard. ''She was never mobbed,'' says Exhale costar Donald Faison, currently on screen in Clueless. ''People would see her and whisper, 'That's Whitney Houston.' And that's it. In New York, it would have been, 'Whitney Houston!''' Further proof the singer felt at ease: She brought along her daughter, 2-year-old Bobbie Christina Brown, who takes never talking to strangers to a new level. ''When she was with Whitney, she would always smile,'' says Faison. ''Then I would go, 'Bobbie,' and she would frown and say, 'I don't know you.' She didn't smile at me once.'' Sounds like she's saving all her love for Mom.