My cat delvered her first kitten at 11:45 pm and the second one at 3:30 am. Ultrasound that we did 3 weeks ago showed 4 kittens. Its 1:45 pm now, almost 10 hours but she isnt showing any signs of labor. She is sleeping, eating, nursing and using the litter as normal. Should I be worried or this is normal? This is her first pregnancy.