Long term storage

[Zerobladeplay]

In my searches on long term knife storage in pelican/apache cases, I see that some people say these foam type cases may cause rust due to moisture being trapped in them. I have moved my collection to an apache case a few months ago and today while removing a knife that I know for a fact I stored dry, I found what looked like little pieces of foam stuck to the pocket clip.

These little foam looking specks were easily scraped off my pocket clip but it made me wonder if I should move my collection back to my knife roll. Anyone else experience this or rust from using this type of foam case long term? I have some desiccants in there for safe measure and my area is not very humid. Maybe this harbor freight foam degrades easier than I thought?