nope.I thought it was common knowledge that dragonstone had a shit ton of dragon glass. Or was that in the books only?
In season 4 Stannis told Sam that there is dragonglass on Dragonstone.
Also, Davos lived on Dragonstone for years and was the hand of the king so he should also know about those mines.
So the fact that there is dragonglass on Dragonstone should be a surprise to literally nobody. both the characters and the viewers already knew about it