Imessages

So I texted someone maybe a day after receiving there message and all of a sudden when I text back the bubble is blue which is normal but usually when I send a message it’s both blue and gives me an indication status “delivered” but except this time I just sent the message and I didn’t receive that “delivered” status underneath the message. Not until a couple days ago I checked back and it says “delivered” now. That message I sent was about a month back but it just now says delivered? Did that person all of sudden unblock me or what happen? They also have read receipts on but it says delivered so I’m assuming either they did actually block me and I sent that message while I was blocked and they never actually received it because I was blocked. And they just decided to unblock me and now it says delivered but they’ll never see it because it never sent. Someone help