Inverting input causing current draw on non-inverting input?
What gives?


a few possibilities - none definitive.

1) bias current isn't linear - datasheets generally don't specify its behaviors other than a typical, max. whether that "kink" is there due to the design or by accident is not clear.

2) bias current can be significant sometimes, like in your case when the discharge current is very small to begin with.

3) assuming a typical long-tail differential input, the bias current is higher than the differential voltage is larger than 0.7v (assuming one pe junction). 

4) your measurement instruments could have introduced additional behavior not present in the actual circuit. the key here is whether the desired time constant is met.

...