Quality forks will have maintenance schedules specified by the manufacturer or brand. The most frequent maintenance is probably changing the bath oil, which is a small amount of ail that sloshes around in the fork legs to lubricate bushings. There is sometimes damper oil to be changed less frequently, and I believe some of my air forks have small amounts of oil dropped into their air chambers.

I've not found a few months of sitting around to be a problem. I suppose after some long enough period of time that something might deteriorate.

Those rubber seals do deteriorate with time and sometimes need to be replaced. I just helped a friend replace his -- on a five-year-old bike -- this spring.

What brand and model fork do you have on your bike?