Thanks Mungus and yes I do have rear a/c but didn't hit the pipes with that screw. I checked mine after noting your post a while back and found that the two a/c pipes actually don't run side-by-side like yours but rather one in front of the other. It's certainly something that needs to be checked before adding screws.
Anyway, that extra screw avoids the pipe's foam cover by a couple of mm. I wanted to get an extra screw inwards as far as practical. I should have mentioned this in my initial post.
Cheers,
Scott

