Perfect Browse has a 'fast preview' technology that allows the images to load thumbnails and previews quickly.
Fast Preview speeds up the loading time by extracting the preview version of the Raw file (every Raw file has an embedded JPEG thumbnail)
These versions can look slightly more or less exposed than the actual Raw file. Eventually the Raw version should load if you leave the Browse interface open long enough and have fast preview turned off. Fast Preview can be turned off in only detail view in the bottom right hand corner.