I've noticed that ARP cache entries stay for long time.
Looking at IP neighbors entry is timely(default 60s) marked as STALE, but it stays as such and no new resolution (no ARP packets in tcpdump) is attempted even if documentation states:
Is that normal behavior?gc_stale_time
Determines how often to check for stale neighbor entries. When a neighbor entry is considered stale,
it is resolved again before sending data to it. Defaults to 60 seconds.