Content Behind Paywall Considered Duplicate

So I've written quite a few articles for another site but those articles are behind a membership paywall. The article is indexed in Google as the title and the first two sentences are visible for non members.

If I duplicate some of the content that is behind the paywall, will that be seen as duplicate content or because the article behind the paywall isn't visible, it's ok?

try to google its hidden text content and see if the article is returned in result-set

jentl3m4n said:

try to google its hidden text content and see if the article is returned in result-set

Click to expand...

Nope, doesn't return the article. Should be ok then?