»Stray Spawners

So yesterday i found a spawner in a dungeon. The deal is, that when i brought a silk touch pickaxe,
it didn't let me mine it saying that: Looks like this spawner is not in the database D=
My friend told me to tnt it so anyway its lost. But for future use...
Is there a way to get those spawners?

 

When you tnt a spawner there is a 30% chance of it dropping.

You can silk spawners you placed, but not ones natural spawned into the world.