munin works fine without Net-SSLeay, should not depend on it. it should consider depending on Net-SSLeay if munin is about to be emerged with ssl use flag on. for me munin-node exited if it could include Net-SSLeay but i had no pem files generated in the munin dir. so i just removed Net-SSLeay, now i don't have my logs full of munin not finding pem files and not using SSL. and then i had to remove Net-SSLeay from munin ebuid manually, but that stands until my next emerge --sync.
just throw 'tls disabled' into your node config. /etc/munin/munin-node.conf anywa, variation coming up in -r2.