I've played some Settlers of Catan myself, and it took me a while to realize what you were talking about.
Well spotted!
If I understand correctly, you chose not to build a settlement next to a tile that produces resources when a 6 is rolled, and by chance, the settlement wouldn't have produced any resources this turn because a 6 wasn't rolled. Therefore, waiting a turn to build the settlement didn't actually hurt you, but it could have.
Yes, By forgetting I had a wood port I could have lost possible resources from a 6 or even more if a 7 came while the cards were still in my hand.
I see similar situations all the time when playing Magic.
I see them rather less. I've played sufficiently few games that I mostly notice the mistakes when the cards drop and my Feral Hydra gets fried. RIP.
I was mostly thinking about mulligans. If you kept a one land hand and go on to win because you drew three lands in a row, that doesn't mean keeping it was the right decision. Conversely, if you do mulligan your 7 card hand and then end up with completely unplayable 6 card and 5 card hands, that doesn't mean that you should have kept your original hand.
A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).