Thud_Driver,
You're exactly right. I didn't think to try two packs. I can check that tonight.
Nope, I probably wouldn't ever do that in flight (probably being the key word), but since I don't know what causes it, I feel safer not flying. For instance, if it happens because of a load, flying would be detrimental to my wallet, not to mention the chance of hitting someone or something. If it's just when I move the sticks back and forth quickly, then I'm probably fine (again, probably).
Of course, when the analog servos I tried aren't doing it and the Futaba 9252 (digital) I've got on my rudder isn't doing it and the 5925's aren't doing it, you'd be hard pressed to convince me I have to run 6v or two packs v.s. replacing the servos. Sure it'd be cheaper, but I'm afraid it would be masking a problem.
Nice to know I'm not alone, though