Credit: AKM Images/Flynet

Another day, another false baby alarm.

Scarlett Johansson went jogging with beau Sean Penn near his Malibu, Calif. home on Sunday. And while fans have grown used to seeing the hot new couple (who've slowly gone public with their romance) out and about together, there was something new about Johansson, 26: a baby bump?!

Nuh-uh, her rep tells

"Scarlett is not pregnant," the rep says in a statement.

What about that supposed "bump" that appears in the photos?

"She's outside running and it's simply the placement of her shirt that is misleading," the rep explains. See more photos from ScarJo's workout.

"She's been training for The Avengers for over four months and is in the best shape of her life."

Meanwhile, Johansson and Penn, 50, are stronger than ever.  The Iron Man 2 actress took Penn as her date to Reese Witherspoon's recent nuptials -- and they made out at a local bar afterwards.

And Penn has the support of at least one ex. "They're great together!" Sports Illustrated model Jessica White, who dated Penn in 2009 and 2010, said recently. "Sean is a really lovely man...[he] needs a good woman in his life."