If you stay in a high humidity country (like Singapore), always assume the gum will stick to the album. In other words you should always have some protection for the gum. If not this is the result.
Even more imprortantly - do not lay your albums flat. Before you realise it, there would be 5 albums sitting on top of another. The pressure will significantly increase the probability of gum damage.
There is another reason why you never lay your album flat. Come back here for future tips.