Check the routing, it appears there is an issue in the next-hop derivation (if you were using dynamic routing like BGP(I presume), check the next-hop or may be there is an entry in the routecache with an invalid gateway ip).
No, you would get destination unreachable or response time out on other conditions. Your response for traceroute indicated was !H, indicating no proper hop, so you should check the gateway IP of the route seen in the route table is valid or not. You can post the route table, and the rtcache for better visiblity. You may also try restarting the routing, flushing the route cache or restarting the device, if you have already determined the gateway in the route table is valid.
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