I'm using an OPA727 as a non-inverting amp with a gain of 5.6, and I'm seeing excessive offset on the output: about -5 mV, for an input of +0.47 Vdc. The offset is a linear function of the input voltage; it's about +0.9 mV for an input of 3.6 mV. I see similar results for four different OPA727s (in separate but equivalent circuits). Power supplies are +3.3V and -3.0V. Gain-setting resistors are 75.9k and 16.5k. Per OPA727 specifications, I shouldn't be seeing even 1 mV of offset on the output. Any idea what's wrong?