Bug in diplomacy

Someone offered me share map but later declared war without cancelling his share map offer. I then used his share map offer to get intelligence on his army, before declaring war again. This was fine as I had ongoing intelligence on his army as he still had share map with me while he had no intelligence on my army as I was now at war with him.

However, when I "binned" the accepted share map offer a few hours later, I lost the intelligence to his army as his country then switched to war.

This appears to be a bug, either one of two ways:

(1) Either I should not have been receiving ongoing intelligence about his troop dispositions after I re-declared war on him as his country should have automatically gone to war with me at the same time, or

(2) The fact that I had war selected against him while he still had share map with me is how the game is supposed to work, but the condition changed when I binned the "share map accepted" trade.

Either way, war should either be mutual or not, and shouldn't depend on whether or not one bins an old trade.

There is a small possibility he just happened to notice he still had "share map" with me at the very moment I binned the old trade and declared war on me at the same instant, but it is very unlikely as he hadn't noticed the "share map" for hours and I checked whether he still had "share map" set directly before and after I binned the trade, he still had it the moment before but it had switched to war the second after, which is why I think it was probably the binning that caused the change. Anyhow, it probably wouldn't be too difficult to verify this is a bug, just by getting a couple of game testers to try it for themselves.