After rupture of a VW Touran CNG vessel during refueling gas company ARAL recommends not to refuel any VW CNG vehicle any further. VW has issued before a recall of about 36000 CNG cars because corrosion problems with the vessels have been known.
For further details see http://www.forbes.com/sites/bertelschmitt/2016/09/16/europe-volkswagen-cars-explode-in-gas-stations/#c533fbb6c6b1 for instance and the included link to a German automotive online magazine.
How such serious events might be excluded? More frequent inspections with suitable determination of state of health might be an approach. Probably the reaction to a similar event with hydrogen would be even stronger.