Problems with auth connection

Hi,

We are having some issues with the auth connection

Version: 2.3.5.1, with MySQL and Postfix

The server is working fine, and randomly after some days, Dovecot fails to auth:

Apr 18 14:25:16 mail dovecot[25013]: auth: Warning: Event 0x126eba20 leaked (parent=0x126eb820): auth-request.c:89 Apr 18 14:25:16 mail dovecot[25013]: auth: Warning: Event 0x126eb420 leaked (parent=0x0): auth-client-connection.c:338

It's neccesary to restart dovecot, and once restarted the server start to work fine again and deliver emails

What do you think i could do?

Thank you, best regards

Fernando