My 2011 SRX ran for one hour while my wife and I dined. I pressed the fob to lock the car and remembered the horn did not honk. I re-opened and re-closed my wife's door thinking it did not fully close, but still no honk. We had the radio playing very low and a really loud truck had started nearby so that drowned out any sound from my engine. I quickly dismissed the lack of honk to some quirk so off we went. Upon return, one does feel rather stupid to realize the engine is running. I have devoted some thought about how this occurred then one day it almost happened again. I had quickly pressed the Start/Stop button to exit but I apparently did not press it the button in far enough to stop the engine. I am convinced I pressed that button the day I left it running, but apparently did not press it "far enough". Note to self, push the start/stop button in all the way until it bottoms out!