Looks good.

What I miss is a information who posted the note.

Some minor design things:

-Some margin between the post and the board on the left and right would be nice when using a card layout like you did

-while replaying I would suggest to make the textfield not on a separate card because the replay and the note are bound together logically

-the upper card does not have a border, but the replay card has a border on the left and right. This looks strange