No, thankfully most authors/publishers know better than to force a font on us. It is not an acceptable publishing practice and rarely occurs. However, some older and scanned books are released in Topaz format and since they are similar to PDF we are stuck with whatever font they use. You cannot include fonts in a mobi file but the newer KF8 format does allow that and occasionally you will get a book with an included font. Just liberate them of DRM and font!