Generally, except when they're hungry or have to potty, the puppies are quite content. They do, however, miss their siblings when they find themselves separated from the puppy pile.
Here's an example of how the pups fuss while they're trying to find their litter mates (this happens to be Master Yellow, but they all do it, and they can all be quite loud about their protests!). Remember, the pups cannot see or hear yet, so they use scent and touch to find each other.
They do eventually find their way, and they do eventually settle down. But they have no trouble demonstrating their distress during the search: