Rick and Daryl had spoken once, over the comms, but Daryl had been hunting, and with everything that had been going on, anything seemed possible. Hallucinations. Shapeshifters or demons masquerading as friends and loved ones. Everything that wasn't supposed to exist.
The fact that Daryl was calling out to him was a good sign, though. It was at least a start. "Hey, Daryl. It's me."