It sounds like he whispered it into a microphone that was very close (like right up on) his mouth. Makes it sound like he's really close and whispering to you, thus the "intimate" quality. It also has a odd frequency response (read: kinda lofi quality) There might be a reason for the YLT influence: they did that really cool show at a baseball diamond with YLT. One Sunday Morning is very YLT-esque: super long, mellow upbeat acoustic jam, whispered vocals, keys