The pair worked together in Wanderlust, back in 2012 while also sharing the screen in the tv series Friends.
So when the two caught up at a SAG-AFTRA, where co-stars Courtney Cox and Lisa Kudrow presented Aniston with an award for her work with St Jude Children's Hospital, Aniston made a very obvious observation: Paul Rudd hasn't aged between sets.
"Oh and by the way, Paul Rudd is 83 years old," she made a wrote on her Instagram, having a cheeky jab.
So what's his secret? Slip. Slop. Slap.
"I am a big believer in sunscreen," he told InStyle.
"I'm not one for tanning. I used to be, back when I was rocking the Depeche Mode look. Honestly, I wear sunscreen not to prevent wrinkles but because I don't want to get skin cancer."