Hi my cat had 2 kittens this morning but she still has one ready to be born but its now been almost 4 hours since the last one was born, its her 3rd litter of kittens. She seems fine and stll contracting,

Hi my cat had 2 kittens this morning but 4 hours later and there is stll one inside. She seems fin and contracting . Is it normal for a cat to go this long between , its not her first litter.