The set of Heroes might be on freeze, but Milo Ventimiglia and Hayden Panettiere are heatin' up -- for real this time! "Hayden's mom adores Milo. She thinks he's so cute," a family friend tells People. "She tells her friends that he's her boyfriend. She's very proud." Milo even joined the Panettiere clan on a recent trip to New York City, where he met Hayden's grandparents. Milo's even got the OK from Hayden lil' bro: "Milo jokes around with her little brother," the source says. "They're buddies."

And while they're hush-hush about their relationship in public, Hayden and Milo are very open about it around their friends and fam. "They're very affectionate and very comfortable around each other," the insider says. "He really takes care of her, even down to the little things like giving her a back massage and going with her to work things."

We guess Kristin Bell doesn't know her gossip that well after all…