"It was a good time," the Twilight star said at the Television Critics Association press tour Monday. "It was a fun few months there."
Lautner and Swift briefly dated in late 2009. The couple had met on the set of the romantic comedy Valentine's Day (2010), which opened in theaters just two months after their split.
Stamos probed Lautner about Swift again in a Facebook Live interview later in the day. The pair were joined by returning Scream Queens star Lea Michele, who got Lautner to admit Swift wrote a song about their relationship.
"That's what she does. She writes songs," the actor said before reluctantly confirming, "It's called 'Back to December.'"