Justin Bieber -- Posts and Quickly Deletes Snuggly Pic w/ Selena Gomez

Justin Bieber let his fans know he's back with Selena Gomez -- but only for a few moments -- as he posted a pic of himself getting cozy with SG ... and then quickly deleted it.

Gomez sparked reunion rumors when she jetted off to Norway to meet up with JB, who is touring there.

As we previously reported ... Selena and Justin have seen each other periodically since breaking up at the end of 2012. We're told he's been "tortured" because she's been giving him mixed signals.

Posting a pic for the world to see and then deleting could qualify as a "mixed signal."