My partner and I made some shrimp pasta last night and forgot to put the leftovers in the fridge. The next morning I promptly proceeded to throw it away, but my partner stopped me and said it was still good to eat. I was very surprised and told him no way should we eat this, and he in turn was very surprised that I would think it was unsafe. He claimed maybe it's a culture thing - he's from Japan and said people do it all the time there, but noticed his friends in the UK (where we live now) are much more careful. He claims it's also common practice in other places he's lived. I told him it's definitely not considered best practice in my home country, but to be fair, food freshness in the US is sometimes questionable (e.g. it's not necessary to store eggs in the fridge in most parts of the world). Am I missing something? Is he just taking a massive risk, or have I been raised with overly sanitised food safety practices? 
The reason you didn't get the numbing effect is because the hydroxy alpha sanshool is an alcohol that is largely soluble in oils not water. When boiled it will come off in the steam and escape the boiling process in that manner. If you distill it, it will collect as an oil not as an ethanol/water soluble product. I doubt that putting the lid on the pot will collect significant amounts, or if they do collect enough to form droplets, they will be as fine oil layer on the surface of the liquid or on the lid of the pot. I note that the extraction protocol mentioned on its wikipedia page includes ethanol and notes that the yield is low (~60%) of the available chemical. Boiling alone in water is not sufficient to extract any significant quantity. 