From the ToS:

"When you submit content to us, you give us (and those we work with) a worldwide license to use, host, store, reproduce, modify, create derivative works (such as those resulting from translations, adaptations or other changes we make so that your content works better with our service), communicate, publish, publicly perform, publicly display and distribute such content.

The rights you grant in this license are for the limited purpose of operating, promoting and improving our service, and to develop new products and services. This license continues even if you stop using our service."

Is this worrisome ?