The Exes Didn't Make Eye Contact Or Speak During The Brief Run-in, But Video From The Moment Shows Hudgens Clocking Butler As She Looks Up From Her Phone, And The Actor Realizing That Hudgens Just Walked By Shortly Thereafter.

Hudgens And Butler Have Both Moved On Romantically Since Their Split, As She's Engaged To Baseball Player Cole Tucker, And He's Dating Model Kaia Gerber.

Before His Run-in With Hudgens, Butler Made A Rare Appearance With Gerber As They Entered The Vanity Fair Party.

The Couple Looked Happy As Can Be As They Posed For Pics, With Gerber Stunning In A Sparkling Celine Gown And Butler Looking Dapper In A Saint Laurent Tuxedo Jacket And Silk Shirt.

MICHAEL TRAN/AFP Via Getty Images

"It's So Crazy, Because Last December, We Were Driving Along And We Were Listening To Christmas Music, And Then An Elvis Presley Christmas Song Came On," She Told Ryan Seacrest At The Time.

"He Had Just Dyed His Hair Dark -- He's A Natural Blonde -- And I Was Looking At Him And He Was Singing Along And I Was Like, 'Babe, You Need To Play Elvis.

She Mentioned The Idea Again The Next Month, When She Came Upon Butler Singing And Playing The Piano.

"I'm Like, 'I Don't Know How, But We Need To Figure Out How You Can Play Elvis.