Over driving opamp inputs
"Wish I didn't know now what I didn't know then.. " (an Ohrwurm for you)

The OPA227 is a bipolar circuit so latchup is not an issue. Usually, the voltage limits are not as important as the current limits, but there is no spec on those.  

The datasheet specifically says: 


  The inputs of the OPA277 series are protected with 1kΩ
  series input resistors and diode clamps. The inputs can
  withstand ±30V differential inputs without damage. The protection
  diodes will, of course, conduct current when the
  inputs are over-driven. This may disturb the slewing behavior
  of unity-gain follower applications, but will not damage the op
  amp


So the differential voltage is not really a concern- meaning that subtle shifts in Vos or whatever are less likely, but the current you're seeing indicates that something else (like an isolation tub for the 1K?) is conducting. 

Can you measure the input current? If it's just a few mA peak I'd not be too concerned, but if it's 50-100mA I'd worry.