Where do you keep your builds ? In the house or out in the shed / garage ?
If they are warm and dry in the house I wouldn't have thought you need worry (let's face it - if they are still NOS and mint now after 25 / 30 years in a bike shop or wherever i think they'll be fine for a good few more in the house
)
If the room / building they are kept in is a little damp though you could always get a de-humidifier