Can't tell you anything about this specific case. Not an uncommon occurence. Our unit has been involved in a couple of similar scrambles in the last couple of months. There are a number of reasons why this happens. Some are technical, and others just down to poor airmanship and awareness (such as speakers selected with very low volume - and not noticing that they haven't heard any r/t activity in 30 minutes whilst overflying busy European airspace during peak daytime hours). Has been happening for years. However, this day and age, with the terrorist potential, such "silent" flights have to be visually inspected.