According to the official website, version 1.4b fixes a bug in polling, adds a max lifetime option, and a compile-time option to touch the pid file on each connection test. Note that a couple sections of the old ebuild are not necessary anymore. See the attached diff for details.
Created attachment 164206 [details] autossh-1.4a-to-1.4b.diff Changes between version 1.4a and 1.4b
Fixed in CVS, thanks for the report!