Our servers by default do not enable any sort of server based caching of your Cascading Style Sheets (CSS).  The majority of browsers however do caching of css, images and java script files which is most likely what is happening if you believe the files are cached.  You can tell your browser to do a hard refresh and re-download everything by doing ctrl+f5 in the majority of browsers opposed to the normal f5 which is simply a normal refresh of the page.