Probes of IP addresses are VERY common. The purpose is to find active hosts with open ports that can be exploited. If your router logged and rejected the probe then you are all set, there is nothing you need to do. As you said, it's a break-in attempt and only an attempt so there is no need to worry. It's the ones that are not logged that are the ones to worry about. You should check your access logs on your hosts to be sure only those hosts you authorized are accessing the servers and that the accesses are for legitimate purposes.
Good firewall management comes with the territory. Open only the ports you need and only from the hosts you support. Secondary firewalls of the hosts on the LAN side is also a good idea, (e.g., Linux iptables, Windows Advanced Firewall), these should be configured and active to block unnecessary ports and to log both successful and unsuccessful attempts and you should check those logs at least once a week.
This is only a sketch of the general policy of firewall management but I thought it needed to be said here. Log inspection will guide you and your experience will teach you the posture you must take regarding threats but know that the threat is always there and is part of the noise level a public-facing router/firewall must deal with every minute of every day.