HI All, Had some new flooring from republic flooring installed on top of the existing wood flooring about a year and half ago. 2-3 months ago i noticed one section where it seemed there was just a tiny bit of flexing up and down on the new flooring. You could barely feel it. Now today in a totally different area of the house there is a section of flooring that is flexing much more. You can visibly see the section of flooring moving up and down when you step on it. It may have been that way for a while, but I'm pretty sure it's relatively recent. Contractor we hired to do all this wasn't the best, so I'm worried that they screwed something up. The only real prep work they did prior to actually installing the flooring was putting down a thin vapor barrier between the existing flooring and new flooring. Any ideas what might be going wrong?