Why has my solid bamboo floor become 'springy'

[dsbp1962]

I had a bamboo strip flooring laid on top of a concrete subfloor less than a year ago. One area (probably with most traffic) has become really springy/bouncy. The bamboo strips were glued when laid but there seems to have been some movement - gaps of about 2mm have appeared, especially in the springy area. Any thoughts? Obviously, lifting the boards in the affected area is a major task as the flooring extends throughout my living and kitchen area.

[Clanad]

My first suspicion when any glue down wood (or in this case, grass) flooring is layed directly onto concrete is excess moisture. Any wood floor lain over concrete demands a moisture test first. Here in the U.S., a calcium chloride moisture test is recommended before beginning installation. The results would tell the installer about the need for a vapor barrier or other installation techniques...