Jake Gyllenhaal and Taylor Swift
Jason Merritt/Getty; Kyle Rover/Startraks
02/28/2011 AT 03:35 PM EST
When exes Taylor Swift
and Jake Gyllenhaal
bumped into each other at one of the Oscars
's most exclusive afterparties
, it didn't look like they were engaging in idle party chatter.
"They were outside near the restroom having a discussion," a guest at the Vanity Fair
bash tells PEOPLE. "It seemed a bit more serious – it certainly wasn't a 'Hi, how are you?' talk."
The musician, 21, and the actor, 30, started dating
last fall but broke up
On Sunday night, Gyllenhaal and Swift were back together for a short visit at the party, and while there was no overt affection between the two. "It seemed like they were catching up," says the source, "sorting something out."
Soon after their chat, Gyllenhaal headed out while Swift stayed and partied with two girlfriends. "They completely kept to themselves," says the guest. "She couldn't be bothered by anyone."
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