Hi there Jenn, Karen is likely spot on. Finn cut his sleep back at 9 mths. I would try to cut the AM nap too, 1 hr. I didn't get on top of that one fast enough and now things are a mess :-) In retrospect, the things that I would try to keep on top of is 1) offering more A time when needed; 2) and recognizing when to cut some day sleep.
I think by waking happy at 40 mins he's telling you that he's had enough sleep in the AM so you need to cut some. For us Finn went straight to nap refusal in the PM, he doesn't waste any time or mess around - he just means business my little monkey lol. So Ethan is giving you a heads up I think, which is really really nice of him. Also, 7 - 6:30 is FANTASTIC so in order to keep that in place it's a bit more tweaking needed.
Hang in there, you are doing so well - I know it's really hard!