Jim McGrath tweeted on Sunday afternoon that Bush will likely remain in the hospital for a few days.
Bush is being treated at Southern Maine Health Care in Biddeford. McGrath said Bush is awake, alert and not in any discomfort.
A hospital spokesperson said on Sunday all information would be released by the Bush family.
The 41st president is spending the summer at the family compound in Kennebunkport. He attended a pancake breakfast Saturday at the local American Legion.
Bush’s wife of 73 years, Barbara, died last month.
The day after his wife’s funeral, Bush was hospitalized in Houston for an infection for 13 days.