Sadly (or happily), hydrogen doesn't explode that easily. The hydrogen autoignition temperature is 500 degrees Celsius. Even if a bullet were to effectively transfer heat, it's still 100 of degrees to cold. Hydrogen got a bad reputation from Hindenburg. It's irresponsible to use only because so many lives depend on it but still relatively safe. The first airship to circumnavigate the globe was a hydrogen zeppelin! And it never spontaneously combusted during its 12 year life apparently.

http://en.wikipedia.org/wiki/LZ_127_Graf_Zeppelin