Wah! ANCHORAGE, Alaska â Alaska state troopers have arrested the mother of Bristol Palin's boyfriend on drug charges. Sherry L. Johnston was arrested Thursday after troopers served a search warrant on a Wasilla home. The 42-year-old Johnston has been charged with six felony drug counts. Troopers did not identify the drug involved in a brief mention on the agency's Web site. Johnston is the mother of 18-year-old Levi Johnston. Alaska Gov. Sarah Palin, the GOP nominee for vice president, announced in September that her 18-year-old daughter, Bristol, was pregnant and Johnston was the father. Sherry Johnston was released from jail in Palmer on $5,000 bail.