I noticed it looks like it has gone done about an inch since I took it out of storage. I have been careful to keep it upright all the time. I'm unsure of what to do about it.
Unscrew the cap carefully when the lamp is completely cool. There should be a rubber disk on top of the glass neck, or stuffed up inside the cap. If there's a date sticker in the cap, try not to bump it, it can flake off. The rubber disk should sit firmly atop the neck, if it seems to be 'off' you can gently pry it out of the cap with a screwdriver, place it neatly atop the globe and re-cap - don't screw the cap down too hard or it'll crack.