The problem actually occured after we added the CRL some weeks ago.. without CRL there was no such behaviour. And of course there are a lot options to mitigate the issue respectively decrease the propability by doing less reloads by decreasing the cycle and/or check if there was a change at the CRL at all..
Anyhow i thought raising an issue makes sense, because from my point of view there is definitively some memory leaking when using tls.reload in combination with a CRL..