I knew this message as well as other trust page warning notes e.g. changed passwords wil last 30 days, check the quoted post below.
I didn't particularly intend for the trust warning to appear for these automatic changes, but it's a niche situation and a bit difficult to fix, so I probably won't fix this unless several other people complain. It only lasts 30 days, after all.
Although this particular post quoted from theymos does not particular talk about the change email but it says all the trust page warning notes.