I am using the AD8221 with +/- 15V supply. I recently put new amplifiers on my board and on power up with no applied input signal the output of one of the amplifiers is ~2.5VDC. Another amplifier has a similar problem with a different output voltage, and two more of them appear fine. The two with problems also seem to be outputting a voltage onto one of the inputs - they each have an input terminal with non-zero voltage even though the other nodes in the circuit are grounded.
I had previously seen other AD8221 chips with that problem and assumed they were broken from having applied an input signal without a power supply. These chips are brand new on a custom PCB, not an eval board.