( Oh and it's not just me she is keeping up. Yesterday, my roomate, sleeping in the room next door told me to her feed the guinea pig (so she would be quiet)
My piggies call out when they the sound of any bag: plastic bag (groceries), fabric bag (fresh grass), paper bag (new toy), etc etc. They call out when they hear my mother in law pass in front of their room, because she always gives them food in between meal times. I'm not sure there's much to do there, they just like routine and they'll remind you if you forget it.
Have you tried feeding right before you go to sleep?