5 year old African Grey first molt??

I have a five year old african grey and he hasnt been eating as much lately for the past three days and today I petted his back and a good 5 to 8 feathers fell out. He has never really molted before jus loses one or two feathers here or there aside from the down feathers.He is still as active as ever, eyes are clear, and dust seems fine. Should I be concerned he has lost a good bit of feathers since?