Your question is ridiculous. Thats like saying "I started prospecting 12 hours ago but it just told me it didnt find any deposits! Why couldnt it have told me 12 hours ago it wasnt going to find anything?"
Because it hadnt happened yet.
Same answer to yours. This is your exact question, just rephrased. Hopefully it sounds wonky to you too.
"Why didnt the game tell me 12 hours ago I was going to drop a door on my head 1 hour ago?"
Because it hadnt happened yet. Standard timeline we all live in. You didnt drop a door on your head 11 hours ago, you just did it now in the present. Thats why it didnt tell you in the past.
Wibbly wobbly, timey wimey... stuff.
On topic: I sure hope you weren't staring at the countdown timer for 11 hours. You should have read the Rules and seen that your more than likely to fail while installing a blast door. My advice? Try again, and again, and again until you take enough damage to fall unconscious.
Edit: My bad, you were only staring at the counter for 11 hours, not 12