Does my veritas r8 have a fault?

Recently moved in to a house with a veritas r8 fitted approx 2 years ago. Has always set/unset without issue. I woke up in the early hours and noticed the strobe on the outside box flashing (it's right by my window). I put my code in to the alarm and it unset as normal but left a zone light illuminated. I checked that zone and reset the alarm. I was home so I know the alarm didn't sound. Does this mean that there is a fault in that zone?