President Bush Phones Chief Justice John Roberts at Hospital

Supreme Court Chief Justice John Roberts, recuperating in a hospital room Tuesday morning after a seizure, received a phone call from President Bush wishing him a speedy recovery. He was expected to be released later Tuesday.

Roberts assured Bush he was fine, said White House Press Secretary Tony Snow, who told reporters that Bush said Roberts sounds like he is in good spirits and doing well.

Roberts stayed overnight in the hospital after suffered what doctors are describing as a "benign idiopathic seizure," causing him to fall down at his summer home in Maine.

He stayed in Penobscot Bay Medical Center overnight for observation.

Roberts was at his home on Hupper Island around 2 p.m. ET Monday when he suffered the seizure and fell. The fall caused minor scrapes, Supreme Court spokeswoman Kathy Arberg said.

Roberts, 52, was transported by boat and then ambulance from his summer home, a journey of some 40 miles. At Pen Bay Medical Center, he underwent a "thorough neurological evaluation, which revealed no cause for concern," Arberg said in a statement.

Roberts was "alert" upon arrival at the hospital, and endured several hours of exams, Arberg said. He is said to have "fully recovered."

Candice Davis, an EMT with St. George Rescue Squad who drove Roberts in the ambulance, told WPFO-TV that Roberts may have hit his head when he fell off a boat ramp, but he had no obvious physical injuries and was alert and conscious the whole time.

Davis said she didn't know who she was transporting until she arrived at the hospital in Rockland and was told who Roberts is.

A benign idiopathic seizure means the episode appears to be harmless and "of no known cause." Steven Garner of New York Methodist Hospital said if Roberts has a previous history of seizures, Monday's incident may be less serious than a newly-emerging problem.

"We just may have a malfunction in the circuits, the way that brain cells talk to one another," said Garner, who did not examine Roberts. Garner said taking medication, drinking alcohol or certain periods of stress can all bring on seizures.

According to Arberg, Roberts had a similar episode in 1993. The White House described the January 1993 episode as an "isolated, idiosyncratic seizure." In 2001, Roberts described his health as "excellent," according to Senate Judiciary Committee records.

Larry Robbins, a Washington attorney who worked with Roberts at the Justice Department in 1993, said he drove Roberts to work for several months after the incident. Robbins said Roberts never mentioned what the problem was and he never heard of it happening again.

Garner added that the report that doctors have said they have "no cause for concern" suggests Roberts does not have a tumor, but that the cause of the seizure should be investigated. He said Roberts could need to wear a heart monitor overnight to track whether surges are being directed to his brain.

Roberts, the father of two young children, is the youngest justice on the court. Justice John Paul Stevens is the eldest at age 87. Nominated by President Bush and confirmed to the court in 2005, he was at the Supreme Court building in Washington, D.C., just last week, though the court is adjourned for the summer.

Roberts spent a couple of weeks in Europe in July, teaching a course in Vienna and attending a conference in Paris.

In 2006, Roberts and his wife bought the house and land on Hupper Island off of Port Clyde, which is part of the town of St. George.

FOX News' Ian McCaleb and The Associated Press contributed to this report.