[psmith2.0]

The more I think about it, the more I realize Artoo and Grogu knew each other.

The timelines match up, and Artoo entering the room is what seemed to cause Grogu to let go of Mando and walk toward Luke. And for Artoo to be doing that excited chirping/shaking thing makes no sense for some random little green guy he doesn't know.

Artoo's the connecting thread in all this stuff, around during the prequels, the Clone Wars, lots of time alongside Anakin and the others, the Jedi temple on Coruscant, etc. He was rubbing elbows, so to speak, with nearly everyone through all these years and events. Being Anakin's droid, he was pretty much a rock star by association himself, so he probably knew tons of people and vice versa...including younglings and Jedis-in-training. Thinking he didn't know, or was at least casually aware of Grogu through mutual acquaintances during that time, is a tough one to swallow.

Does anyone here get all giddy and tremble with excitement upon meeting someone you don't know? I sure don't. Or do you have that sort of reaction when you see an old friend again after a long time apart?

Exactly.

They looked like two "people" who knew each other long ago, and, after separated by tragedy and awful events, they were just reunited. If they didn't know each other, Artoo would've just rolled in, stood at Luke's side and maybe offered a single "beep" of hello/acknowledgement. But he was carrying on a full conversation and doing all the things that have been established for 40+ years that Artoo does when he's excited or "happy" about something.

In all the reaction videos, articles and reviews I've taken in the past 24+ hours, I've not seen/heard anyone talking about this.

There's no reason Artoo would be that upbeat, animated and "talkative" in that scenario, IMO, unless he recognized someone he knew long ago. For all we know, Artoo might've been responsible, or at least one of several, for getting Grogu to safety when the temple came under attack? We know how loyal and brave he is, so it's not a stretch to imagine him being involved in such a thing when everything started to hit the fan.