You stand the bottles up right for a few days to allow the corks to expand from the compression of corking, to ensure a seal... not to let compressed air out. We skip this step when bottling at the winery I work at and package them in the case upside down as they come off the line. Can you imagine unstacking several pallets of wine and flipping the bottles after three days, and then stacking the cases back onto the pallets? No thanks. As far as I know, we have not had a leak yet (we use natural corks for what it's worth).
The info on the Oxygen ingress of closures originally comes from a study done at Victor Segalen Bordeau 2 University. I've also read it in Practical Winery and Vineyard journal, and was also repeated in one of my enology classes. I've never had any cork, be it synthetic, natural or agglomeratd, pop due to temperature change or any other reason. Usually this is caused by a secondary fermentation inside the bottle. How big of a temperature swing did you expose these wines to?
I have had a solid bung shot out of a carboy due to thermal expansion though. The carboy couldn't have been open for more than a day or too, but it turned my Frotenac/St. Pepin blend a bit more brick red than I would have liked. Luckily it still retained some CO2 and wasn't completely ruined. I've stopped using solid bungs on my carboys after that incident.