Why did i get a white bootup menu?

[AC Question]

I was outside using my phone (HTC One) when it cut off at 93% (it's a battery issue that I intend to have fixed). When I got back to my dorm and plugged it in to the charger, the battery logo showed up and then I got a white boot up menu. I remember seeing 'security warning' in orange and 'boot in recovery mode' and a few other boot options in green. The screen timed out before I could touch anything and I held the power button to turn it on. My phone was exactly the same before it cut off. Why did that screen show up and should I be concerned about that warning? Other than the battery thing, my phone is relatively functional.