I don't believe there is a thermal issue, as I can run this circuit all day, and it will give me the correct output current of ~50mA, but only on transient do I see unexpected behavior. There is a proper connection to the rails of the op-amp, and I have even removed the buffer at one point to measure the transient response. The problem is still the same... A pulse of opposite polarity, acts exactly the same EXCEPT for a very small pulse of approximately +/- 10mV, then it seems to have a proper transient response (critically damped ...)