The veteran comedy actor posed for a new snap this weekend that was posted by the owner of an Indian restaurant in London called Darjeeling Express ... a place he's apparently stopped into before, and brought a pal with him this time around -- Mr. Dan Levy.

Paul's filming the new 'Ant-Man' installment there -- Dan appears to just be in town.

Anyway, the restaurant (and its owner, Asma Khan) posted a sweet photo of Paul and Dan breaking bread in their establishment Saturday, and even though they seem to have hosted PR before ... they were still starstruck, writing in their caption ... "When Paul Rudd returns for dinner to the restaurant and this time brings the lovely @instadanjlevy with him! ♥️❤️."

The photo has since gotten Paul and Dan trending -- with the former being compared to an ageless angel ... because he seriously looks young in this specific pic (Paul's 52, BTW).

They threw up a second shot of Dan on his own, and said they were glad he dug the grub. Still, it's the duo photo of the two of them at the table that's got people chirping.

As you might imagine, the jokes were flying online ... with folks saying they've aged more in the pandemic than Paul has in the last 5 years -- and that may well be true, 'cause he doesn't seem to have a wrinkle or a crack on his face ... well, at least in lighting like this.

Another photo Darjeeling posted mere weeks ago -- from Paul's initial visit, apparently -- paints a somewhat different picture. It's way more well-lit ... and, yes, Paul certainly looks older here. Still great for his age and all -- but it's almost like he went back in time for this weekend's photo-op ... it feels like 2 different people showed up over the course of 2 weeks.