somewhat more concerning is that the threshold (vih) of the pin has shifted up by about 50mV. ~1.36V -> 1.41V. EDIT: i measured it again with the curve tracer instead of directly with the voltmeter/ammeter combo, and it appears to be identical to the other GPIO pins. it's tricky to measure the threshold with the source current bug affecting the measurement.
hmm, there does seem to be an effect on the Schmitt trigger circuit. GP0 has a lower falling threshold than the other pins when Schmitt trigger mode is turned on.