Today I received an email from Apple informing me that "Your Apple ID was used to sign in to iMessage on an iPhone 4". I have not personally changed my iMessage setting on my iPhone 4 in a long time (months and months). I promptly checked Settings > Messages > iMessage on my iPhone 4 and saw that it was with the ON position. I slid the ON to OFF and back to ON again where I was asked to enter my Apple ID and my password. After doing so I received (within minutes) a new "Your Apple ID was used to sign in to iMessage on an iPhone 4" email message stating the change.
I have logged into my iTunes account and checked my Manage Devices panel to double-check the devices using my Apple ID and found that there is no extra unknown device present. All that are there are devices I recognise and have authorised to use my Apple ID.
Has Apple just deployed a messaging mechanism that has just happended to send me an email notifying me that my iMessage is ON despite it's being on for months, or is there something more sinister taking place that isn't yet apparent in my iTunes account where I'd expect as first port of call to see if anything was array?
I have also checked my Apple ID associated Purchases and there is nothing odd or untoward there that would cause me to be alarmed.
In any case, as a precaution, I have chandged my Apple ID password, just to be confident and with peace of mind on my part that my iTunes account and iMessage feature is safe and secure under my control.
As expected, iMessage onmy desktop and iCloud prompted me automatically for verification. iCloud on my iPhone 4 follwed suit and iMessage went through the "Waiting for activation..." protocol that I expected it to.
p.s. it would be helpful if Apple's email notification message "Your Apple ID was used to sign in to iMessage on an iPhone 4" indicated the time and date of each sign in). As is, there is no indication of when a sign in using my Apple ID occurred in the message sent to me from Apple.