sad ferret??

Question
I got my first ferret in December, 6 moth. old female, from pet store where she lived for her entire 6 months. She used to play games with us hide and seek, chases, dragging towel you name it. She got everything, big cage - custom build, toys, around January she stop playing, all was she interested in is just to climb inside the sofa and sleep with her favorite toy. She eats well, poop regularly so we figure she may be bored with us adults, so we got her friend to play with another 3 months old female ferret.
In the first day there was huge change in her attitude towards to us, she never bite anymore she become how we called a grandma, very mellow. She was playing and chasing for a while and then she get back to her old habits in the sofa...  The new one is very playful and always licking and chasing and inviting for play the other one, but sometime the old one just laying flat and taking all the abuse with no movement, till she get it and just walk away. I don't think she is sick, she seems well, her fur is thing good colors, no swelling anywhere. Help us we love them both and lately we trying to get more attention to the older one just in case she got some jealousy issue.
Any idea???
Thank you for your help _lucie@yahoo.com

Answer
It could still be a medial issue and I always suggest a vet visit with a change in behavior.  It could also be that she is forced to play when she doesn't want to - maybe earlier or later in the day.  Additionally, she is a bit older now and may not want to play as much.  Still, have her checked out by the vet first to make sure nothing is wrong.  Then try some enrichment with her.