My girls had the same Pediatrician since birth. They only go usually once a year for physicals, and on rare occasion have been in maybe one thing in addition to that.
One of my girls is turning 8 this year, and they had a male doctor. I felt as they got older they may be more comfortable with a female doctor, so I switched them last year.
I can understand wanting to keep them with a constant doctor, but I think a valid reason for switching isn't a big deal either.