SOP with all falvorings and ejuices should be to shake extremly well before useage. Componets in the flavoring(s) can sperate ,many contain alcohol which floats to the surface and is the primary reason for airing out new juices for 24-48 hours.
I use many FW flavorings and IMO they are no worse about seperating than other flavorings. Mount Baker Vapor uses FW for all otheir juices and there are threads here on ECF on them in the General Ejuice Forum and also in the DIY Forum.