I've noticed that sometimes the post change history updates especially slower, with a delay of several hours. For example, the history of post #5480528 currently states that the last edit was by me 8 hours ago adding a few tags including black shirt, however, if you look at the actual post, there're tags such as dress shirt added later on that are not found on the history page.
I've checked logged off to make sure that I am not the only one getting this. There also weren't any delay on other history counts such as wiki history or artist commentary history when the post change delay happens. I was assuming there're some kind of site updates/maintenance operating that caused these delays and moved on, but recently they've been annoying me a bit more as I need to constantly check the post change history to stay up-to-date when I'm tagging. So I want to know what exactly is this, just to make sure?