security indicator light blinking 2012 itouring
 

I have a pre-sky-activ model, 4-door bought new in 2011. I do not have the advanced key and to my knowledge don't have anti-theft technology installed. I have the retractable key and keyless entry.
This evening when I turned off the engine I thought I heard an unusual beep and then noticed that the Security Indicator Light was blinking about every 2 seconds. I tried a few things and found that it blinks whenever the engine is not running, whether the doors and trunk are locked or unlocked, manually or via keyless entry.
The car starts up ok, using my usual key or the spare key.
I may be losing it but never noticed this before. Is this a security feature that just turned itself on? Will it run down the battery? Do I need to take it to the dealer?
Thanks --

Howard