It's possible the EQ points would shift with the position of the feedback control, but I would be surprised. It depends upon how the feedback control is implemented, and I have not seen a schematic of the Little Stubby so I can't give a definitive answer.
I do have schematics for quite a few tubes amps. Usually feedback is between the output transformer and the phase inverter, or the tube driving the phase inverter. Since the phase inverter is after the tone stack, modifying the feedback won't change the frequency centers of the tone controls. However, in some amps the feedback is tied into one of the tone controls. For example Hiwatts and Matamps tie the feedback into their Presence control. But the Presence control is tied into the phase inverter, which is still located after the tone stack. IMHO this sort of Presence control is not a pure tone control as it also adjusts the amps feel and distortion characteristics somewhat. Also I wouldn't be surprised if this sort of feedback control changed the frequency response of the amp.
I would bet the the Little Stubby tone stack is a variation on a Fender tone, so the frequency centers will shift a bit depending upon the position of the tone controls. I.E. the tone controls should interact with one another somewhat.
