Actually, if your question is about an obscure enough topic, you'll get your own question within seconds on Google. It's a kind of loop - search on Google desperately without finding anything; turn to SO and ask a question. Since probably nobody will answer soon, in the meantime search more on Google... and you find your own question on top (and feel just a bit more desperate).
He said he ended up on his answer, therefore it's something he knew but forgot. Nonetheless your observation still holds, as the obscurity of the topic increases the chance of such coincidence both by the scarcity of content on the matter and because he is more likely to forget little used information
