Warping and Magic Items

I have no doubt that this has been answered somewhere in the forum already; I just can't find it. My apologies for any duplication.

What I wanted to know is with respect to items, is Warping counted based on the final level of the item or on the underlying enchantment in the item? For example, what if uses per day moves the total level of effect to 30?

Consider an item to protect grogs from fire. It has the base spell Ward Against Heat and Flames, a level 25 spell that would not otherwise cause warping. But, put it in an item and the level changes. Say I give it 12 uses/day. That's +4 to its level raising it to ReIg 29, still below 30. However, if I make it 24 uses/day, that brings it up to ReIg 30, which is high enough to cause Warping.

So, is the Warping trigger based on the base spell (ReIg 25) or on the final device (ReIg 29 or 30)? I could see the arguments either way.

from Legends of Hermes p.112

I believe that there is another similar statement in Through the Aegis.

Thanks much for the clarification.