Earn a masters while a post doc?

[static_ninja]

I was out with some friends-of-friends the other night and someone mentioned that he had heard of postdocs for biology-ish PhDs that were coupled with earning a Masters of Public Health.  I tried googling this once I got home and had a lot of trouble finding anything.  Does anyone have any information about this type of combination and/or suggestions for ways to search better?

For the record, I'm in America and my friend thought that he'd heard of this being offered at a school on the east coast.