Nullstone Gargoyle + Welder + In Response

[Rastadon]

I'm playing Burn vs Welder Survival on MWS. I play a Price of Progress. In response he Welders out a Nullstone Gargoyle and says that the spell is countered. Nullstone Gargoyle says that "Whenever the first noncreature spell of a turn is played, counter that spell." I said that playing stuff means putting spells on the stack, and my Price was on the stack and played before his Gargoyle was in play. He didn't offer much of a counter argument, or atleast one that I could understand, but I think the point that he was making is that playing stuff is the same thing as resolving stuff. Who's right here?

Thank you

[parallax]

I'm playing Burn vs Welder Survival on MWS. I play a Price of Progress. In response he Welders out a Nullstone Gargoyle and says that the spell is countered. Nullstone Gargoyle says that "Whenever the first noncreature spell of a turn is played, counter that spell." I said that playing stuff means putting spells on the stack, and my Price was on the stack and played before his Gargoyle was in play. He didn't offer much of a counter argument, or atleast one that I could understand, but I think the point that he was making is that playing stuff is the same thing as resolving stuff. Who's right here?

Nullstone Gargoyle has to be in play when you play your first non-creature spell in order to trigger. Once you have played a spell, putting a Nullstone Gargoyle into play in response will have no effect on that spell or any other spell that turn.