Have you done any renovations lately? You may have issues with drywall made in China

Not to be an alarmist, but if you have had any renovation work done in the past few years, you may want to at least investigate what kind of drywall was used in your project. You may have heard the news reports about defective drywall which was imported from China and used in construction projects in the U.S. Reports vary, but it seems that the first of the defective drywall was imported in 2001 and none has been imported since 2008. Although the dates of import are relatively well established, the dates of installation are not. Homes built or renovated since 2008 may be affected as well.

While most of the problems so far seem to be in southern States, it is my understanding that the “tainted” drywall has shown up in 32 states as well as in DC. Heat and humidity serve to exacerbate and accelerate the manifestation of the problems associated with this drywall. It is likely that many homes located in areas that are not exposed to high heat or humidity have not begun to experience issues. Because the symptoms have not yet become evident, the issue hasn't surfaced. This assumption is supported by several studies that are being conducted on problematic drywall.

Here is a good website from HUD: HUD Drywall Info