I wouldn't have thought it would be included by default - check to see what mime type is being sent by the web server when you access that file. If it's identifying as html the the crawler will store and index that.
It may also be that you just need to add less to the rejected types. The default list is below and includes css but not less
crawler.reject_files=asc,asf,asx,avi,bat,bib,bin,bmp,bz2,c,class,cpp,css,deb,dll,dmg,dvi,exe,fits,fts,gif,gz,h,ico,jar,java,jpeg,jpg,lzh,man,mid,mov,mp3,mp4,mpeg,mpg,o,old,pgp,png,ppm,qt,ra,ram,rpm,svg,swf,tar,tcl,tex,tgz,tif,tiff,vob,wav,wmv,wrl,xpm,zip,Z
