I keep hearing stories. But the truth remains, there is no correlation between radio waves and a gas cylinder that can cause it to trigger fire and explosion.
Yes, the radiation of cell phone is always high, but there is no evidence that says when it connects to gas flame it will result to explosion .
However, for you to be sure and safe, if your gas cylinder is switched on, do not use it for calls or avoid any incoming calls. If you may, just make sure not to stay there close. You have to shift from the area of gas cylinder and make your calls. if not, maybe just maybe gas may explode.
I have heard different stories that it kills many people when receiving call near a light gas. Can't confirm yet. But please, don't try it.
No one have been able to explain the physics behind it if it causes fire and explosion or not. If you want to use your phone touch light while cooking with gas, just switched to fight mood so that call won't enter.