Justin Bieber Smiles, Blushes When Asked If He'll Propose to Selena Gomez

Justin Bieber didn't give a verbal answer when asked if he and Selena Gomez are gonna get hitched ... but his facial expressions ... well, arguably telling.

Paps got Justin Monday at Il Pastaio in Bev Hills, where he posed with some servers and hugged it out with Gigi and Bella Hadid's pops, Mohamed, on the way out.

Watch his reaction when a photog asks if he's gonna propose to his on-again, off-again girlfriend -- with whom he recently got back together. A blush is worth a thousand words.

Oh, and we also got JB the same day and asked what he wanted for Christmas. Aside from a possible engagement ... sounds like he's mulling over a Biebs Institute.