Renate -
Yes, she could be producing milk caused by breast stimulation.  I do know of
women in *ahem* passionate relationships who find they start producing drop of
milk because of all the breast stimulation.
She might also get her prolactin levels checked.  My big concern would, of
course, be breast cancer.  She should see her physcian asap about a mammogram
or ultrasound.
Cynthia D. Payne
LLL of Berkshire County MA