Are other people seeing this? I use the web interface all the time, and deliberately avoid services that force Facebook sharing/integration.
It certainly isn't forced, but it is probably enabled by default if there is a facebook account with the same email.
http://help.pandora.com/customer/portal/articles/24775-disco...
That same day I quit Pandora. At that point in time, they did not even have a mechanism to kill your account, so I had to email the company personally.
I quit my Facebook account not long after.
I refuse to willingly partake in a surveillance society.