DHCP Server unknown entries

I keep getting those lines (sometimes 4 ,5 each day) on my Log Summary. My network is 10.0.0.* Something to be concerned ? thanks.

 Unknown Entries:
    reuse_lease: lease age 0 (secs) under 25% threshold, reply with unaltered, existing lease for 10.0.0.21: 1 Time(s)
    reuse_lease: lease age 3 (secs) under 25% threshold, reply with unaltered, existing lease for 10.0.0.27: 1 Time(s)

Since a while the dhcp server logs if a client ask too early for a still existing lease. There is usually nothing wrong eith the network. Maybee this clients has simply rebootet or restart the dhcp client.

Please create a bug that this message should filtered and not logged as unknown.