Long time lurker, new poster though!

I've got two servers running Stunnel v2.54 (yet to upgrade as I've been waiting for an x-forwardfor patch to become available).  I noticed recently that one Stunnel nodes had exited, requiring a restart.  I'm not sure if it's a co-incidence, but I've only just changed the cert on both installs last night.

This, of course, is very concerning as it's only just become a problem, but being the core SSL endpoint, it knocks our server offline until it's restarted.

Now comes the interesting bit, I've run the SSL Labs SSL Health check at https://www.ssllabs.com/ssltest/ just to see if anything comes out of it, and noticed that without fail every time it runs (and the first server is online) it'll know Stunnel offline as it goes through it's tests:
"Testing TLS v1.0...."
"Testing TLS v1.2...."

This was noticed by a fluke, but appears to happen every time I restart and then rerun the test.

I'm not getting any segfaults, or errors from stunnel, and it only affects the one (primary) server.  Can anyone shed any light as to what might be causing it, how I can get any more info out of stunnel, or better yet, fix it completely?

Thanks all

Alfie