Hey, I wasn't implying that you were, but they're bent up to fit the marker that the bottles were fitted to at the time of fitting (which would be your inferno, right?).
If you've got a new bottomline, then the threads might be different enough to make the bottle screw in further... or not as far... either way, your anti-syphon becomes a syphon... geddit?
If you WANT liquid CO2 flooding your nice shiny new Impy then go ahead... I was just saying that for £4, it's peace of mind and not all that hard.
What you *could* do if you're not able to get it checked out before you next play is to screw the bottle back onto the original marker that the anti-syphon is set for, mark the top of the bottle yourself, then screw it into the impy and see if the mark is in the same place. If so, then chances are the anti-syphon will at least be as good as it was for the inferno, and will work (assuming it was set correctly for the inferno).