Spoiler Alert for Star Wars: Shattered Empire #3 from Marvel Comics, on shelves October 14, 2015. Do not read further if you don't want to be spoiled! It's an excellent issue full of huge moments, so read it first then come back and speculate with us!
In Star Wars: Shattered Empire, we're getting one of our first looks (alongside the novel Aftermath and the mobile game Uprising) of the post-Return of the Jedi universe in the new canon. The comic book series, written by Greg Rucka with art by Marco Checchetto, Angel Unzueta, and Andres Mossa, takes our heroes into the weeks following the Battle of Endor, as they fight the Imperial remnants and try to begin establishing the New Republic. The series also introduced two notable new characters: Shara Bey and Kes Dameron, who are the parents of Poe Dameron, the Resistance Pilot in Star Wars: The Force Awakens played by Oscar Isaac.
And all of that was big enough already. We see that the evil of the Empire trickles down amongst the ranks, not just from the Emperor and his Sith Apprentice, and that even with him dead, there are many ways his presence can still be felt. But in the pages of Shattered Empire #3, it's another Sith Lord whose presence is felt: Darth Maul.
The issue is full of "holy sh*t" moments, but when Princess Leia, Shara Bey, and the current Queen of Naboo Soruna enter an old, locked hangar on Naboo, they see several of those old yellow Naboo Starfighters, which they're hoping are still operational. For Leia, though, she sees something else - or at least senses something.
"Do you feel that? I feel... cold..." Leia says as they enter the hangar. An image of Darth Maul's face, meanwhile is plastered over her while she speaks.
This is significant in many (and many possible) ways. First, it's the next step in Leia's becoming attuned with the Force. She is strong with the Force, but we haven't really seen her use it in canon. Here, because of her strong ties to Naboo, she's likely more linked to it and thus getting more of those Force-y vibes. That's the most likely reason she sensed Darth Maul. His time on Naboo was significant, after all.
It's not the first time she's had a Force vision on Naboo, either. In Princess Leia #2, when she encountered a stained glass portrait of Queen Amidala (her birth mother), she saw the image turn and look at her, something her non-Force sensitive companion didn't perceive.
Of course, there is another possibility, as well. In the canon of Star Wars at this time, Darth Maul did survive the Clone Wars. Despite being captured by Darth Sidious (Palpatine), he eventually escaped for good, and the then-nearly-Emperor let him, considering him no longer a rival.
During the time between getting sliced in half in The Phantom Menace and re-emerging in The Clone Wars, Maul was reclusive for years, surviving basically on pure hatred and dark side Force energy. It is conceivable, then, for him to do that for another 24 or so years, and that Leia didn't have a vision or feeling of a memory, but of the living, exiled Sith Lord himself. Again, this isn't likely, but it is a possibility supported by the current canon.
In the end, this is much more about Leia gaining more strength in the Force than about teasing anything else. It could give us indication that in Star Wars: The Force Awakens, hitting theaters December 18, 2015, Leia could be a full-on Force user, or dare we say it - even a Jedi.