Billy Joel sings 'Uptown Girl' to ex-wife Christie Brinkley

If only every divorced Hollywood couple could be as cordial as Christie Brinkley and Billy Joel.

Cordial is actually an understatement: the supermodel was front and center at one of her ex-husband's recent concerts, where he serenaded her with Uptown Girl - the song he famously wrote about her. Now how cute is that??!

It really made her day - check out her lit-up face in this pic she posted on Instagram:

"He's still got it!" Brinkley wrote alongside the pic.