I've checked my Lotus tween and it too has nylon in the back pocket and cp pocket... I'd never noticed before... whereas on the hip the nylon lining was a real downer for me (I still love my hips and have got over it, but still was a bit of a moment)

Thats one thing about my BB packabe - it has satin lining everywhere! so beautiful (but heavy, satin may contribute to heaviness?)