That neighbor who quoted my deck board spacing back to me 3 months later

I was rebuilding my deck last spring and my neighbor Bob walked over while I was setting the gaps between boards. He said, 'You're doing that wrong, you need a 1/8 inch gap not 3/16.' I brushed him off and did my own thing. Fast forward to August and the boards started cupping pretty bad from moisture trapped in the wider gaps. He came by again, just looked at the deck, and said 'Told you so' without any smugness, just matter of fact. I asked him how he knew and he said he'd built 12 decks over 30 years and learned the hard way too. Have any of you had a neighbor or random person call something out that you ignored and then regretted it later?