leap test should check for certificate expiry
nagios is checking the certs as well, but in the case that those are expired as well, you won't have the ability to check nagios.
"leap test" should check both commercial and internal certs for expiry
Oct 3 10:38:47 couch01 stunnel: LOG3[9257:140205519390464]: SSL_accept: 14094415: error:14094415:SSL routines:SSL3_READ_BYTES:sslv3 alert certificate expired
(from redmine: created on 2014-10-03, closed on 2014-12-10)