Yikes! I missed that!
I just read an article yesterday that said at that age they shouldn't be away from their mothers for more than ten minutes all day:
"From 3-4 weeks your puppy begins the most critical social
development period of his life – he learns social interaction
with his littermates, learns how to play and learns bite
inhibition.
He’ll also learn discipline at this point – Mom will begin
weaning the pups around this time, and will start teaching them
basic manners, including accepting her as the leader of the pack.
You can begin to introduce food to the pups starting around the
4th week – transition gradually as Mom weans them. Continue
handling the pups daily, but
don’t separate them from either Mom or litter mates for more than about 10 minutes per day. Puppies that are removed from the nest too early frequently are nervous, more prone to barking and biting and have a more difficult time with socialization and training. Puppies need to be left with Mom
and siblings until at least 7 weeks of age - and preferably a
little longer - for optimum social development. Experts say that
the best time in a puppy’s life to learn social skills is between
3 and 16 weeks of age – that’s the window of opportunity you have
to make sure your puppy grows up to be a well-adjusted dog. It’s
extremely important to leave your puppy with Mom and his
littermates during as much of this period as possible."
http://petcaretips.net/stages-puppy-development.html