There must be a lot of mistletoe on the set of Gossip Girl. The New York Daily News is reporting that the stars who portray lovebirds Dan Humphrey and Serena van der Woodsen may be love struck in real life as well!

The Daily News reports that the adorable Blake Lively and Penn Badgley — whose uptown / downtown relationship keeps the hit show sizzling — have quietly started dating in real life. Please, Daily News, don't jinx it!

Regardless, these two know each other well. Blake has known Penn Badgley since the age of 11, as stated during an interview with Tyra Banks.

A real-life romance for Penn Badgley (Dan) and Blake Lively (Serena)?

"No one is really supposed to know that," laughs a Gossip Girl insider (not to be confused with this website). "I was told by a friend of the family."

Their new relationship has meant Blake Lively, 20, having to disentangle herself from her former boyfriend and Burbank (Calif.) High School classmate, actor and model Kelly Blatz.

Lively and Penn Badgley, 21, were spotted shopping together December 17 at ABC Carpet and Home on Broadway, looking every bit the couple.

Are they really dating? Or just the subject of celebrity gossip like Chace Crawford and Leighton Meester? Guess we'll have to stay tuned!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.