In reply to BnB:
How old are your ropes?
The new UIAA specifications only came into play last year, so if your ropes are older than that then that's probably why. I have to admit that all my old dry ropes have done exactly the same!
On the note of the UIAA specs, the impression I got not just from Edelrid, but from other rope manufacturers, was that it has now become far more difficult to achieve 'dry' status. Hopefully this equates to a higher standard of performance in wet/wintery conditions, but I'll leave this to a suitable gear reviewer to decide - I'm trying to avoid those sorts of conditions currently!