I have noticed that both my 4 month old boys hunch up their backs every once in awhile....it isn't everyday....they are both eating, drinking, pooping/peeing......eyelids are good. They seem happy and playful, but every now and then I notice they do this.....it only last for a few seconds and then they relax and go about their business. They were womed by the vet last month and then I wormed them with horse paste 2 weeks ago. Is this anything to worry about???? Just don't want to let something that could be serious go ignored......they have been doing this since I brought them home 7 weeks ago....they were treated for cocci when I first got them home, but they both have tested clean for it and worms. Thanks for sharing your knowledge!