'How I Met Your Mother': Alyson Hannigan and Josh Radnor Reunite

How I Met Your Mother stars Alyson Hannigan and Josh Radnor reunited on Monday, giving some fans fresh hope for some kind of reunion. The two stars both posted a selfie together on Instagram, revealing that they had had lunch together. Immediately, the comments filled with speculation about possible cameos on How I Met Your Father.

Hannigan and Radnor stood arm-in-arm on the street when they took a selfie together during their meet-up. It's not clear where they were, but they stood in front of a store with a poster for "CigarBros" in the window, evoking some of the hijinks in the earliest seasons of their sitcom. Both smiled and spoke highly of each other in their captions. Hannigan's read: "A very special lunch guest today."

Radnor was a bit wordier, writing: "Well look who I had lunch with today!! None other than [Alyson Hannigan] herself! It was delightful. So sweet to reconnect and drop in and talk about all the things. And her tremendous sweater just added to the magnificence. Love this gal forever."

Radnor's post got some comments from other sitcom stars. Actor Kyle MacLachlan got the top comment, writing: "Ahoy! The Captain approves this meeting!" Fans were quick to note that MachLachlan has already made an appearance on the spinoff series How I Met Your Father. Meanwhile, the official Hulu account left a comment as well.

"Please tell us lunch was at MacLaren's," the streamer wrote. Hulu's spinoff series features a healthy dose of Easter eggs and nods to How I Met Your Mother, including the apartment that served as the main setting for much of the series. That means the adjacent bar, MacLaren's, has also made an appearance here and there, though the characters do not visit it as often as the original ensemble did.

As for the possibility of cameo appearances, there is nothing new to report. Season 1 of How I Met Your Father ended with a cameo by Cobie Smulders as her old character Robin Scherbatsky, while Season 2 is teasing out a story arc with Neil Patrick Harris as Barney Stinson. Radnor has been vocal about his willingness to appear on the show, and new star Hillary Duff has spoken in favor of the idea as well.

"I had a really sweet email exchange with Hilary Duff," Radnor revealed in an interview with Newsweek in January. "We kind of went back and forth about being the 'I' on How I Met Your dot dot dot... [Hilary] has said publicly she'd love to have me on, so I wouldn't turn down an invitation."

How I Met Your Mother is streaming now on Hulu. How I Met Your Father is there as well, with new episodes of Season 2 airing every Tuesday.