Hi,
This is the default RIP behavior.
RIP hello time is 30 seconds. If a hello is not received from the neighbor after 180 seconds (invalid timer)it advertises it with 'infinite' metric, 16 in RIP case. This way it advice its neighbors not to use that 'dead' route.
The 60 seconds timer is called the 'flush timer' or the 'garbage collector timer' and it is used by RIP only as a routing table cleaning tool.
Another advantage is that the route will remain in the routing table after the flush timer expires, that way if a new hello is received, the route still will be on the table.