Okay, I have a long tailed pair (actually a Gilbert cell differential output), presumably diffused resistors to Vdd, and there's a DC offset and tempco of that offset. Current is about 1mA on each side.
I tried nulling the differential output voltage by adding a high resistance to the lower side to Vdd, and the tempco seems about the same magnitude, but the sign flips.
Is this to be expected? Lucky chance? Experimental error?