Proxol warns about closing active connections

Hello,

I receive many warnings in Warn log like this one:

org.logicalcobwebs.proxool.openfire - #0016 was active for 916040 milliseconds and has been removed automaticaly. The Thread responsible was named ‘socket_c2s_ssl-thread-4’, but the last SQL it performed is unknown because the trace property is not enabled.

Is it a correct behaviour? How can I get rid of these warnings?

Thanks!

Could you kindly provide more details? Like version installed, users registered, when this problem started, etc. Which database being used?