[Bro] What does it means this alert?

[C. L. Martinez]

On Tue, Oct 30, 2012 at 9:09 AM, C. L. Martinez <carlopmart at gmail.com> wrote:
> Hi all,
>
>  I have installed bro-ids components on a CentOS 6.3 host. All works
> as expected but from time to time I am receiving alerts like this:
>
> nice: which:: No such file or directory
>
> --
> [Automatically generated.]
>
> What does it means??

It seems that the alert is triggered when bro rotates logs ... Is it
possible to avoid this alert??