Not sure if anyone else has noticed this but the new memory foam liners on the 07-08 Buzzs are prone to mildew underneath.
This is due to the memory foam holding moisture/condensation underneath it especially in this hot weather we're having.
Usually the memory liner is used from birth to 12 months so by the time you'd come to remove it and replace it with the XL liner it would be too later and the damage would have already been done.
I have removed mine recently and found the beginnings of mildew on the seat and it was soaking wet between the seat and its plastic base.
To remedy this I have placed a flannel between the liner and the seat base, hoping this will keep moisture away from the seat liner itself.
Hope this adice has been of use to any Buzz owners (before its too late!)