kernel ignores default route?

[Michael R. Wayne]

One of my machines is doing something I can not understand and may
have uncovered some form of bug.  The kernel appears to be ignoring
the default route. Had several people look this over, we can't
determine where the route is being hidden. This is 7.4-RELEASE-p2.
I suspect that rebooting the box will clear the problem but I would
REALLY like to figure out why the routing table is not being followed.

I have two routers, on the same ethernet at:
148.59.4.1 (default)
148.59.4.3 & 139.171.192.26
148.59.4.2 (FreeBSD box)

This is correct (see routing table below):
   > traceroute -n 148.59.48.1
   traceroute to 148.59.48.1 (148.59.48.1), 64 hops max, 40 byte packets
    1  139.171.192.26  7.366 ms  4.748 ms  6.879 ms
    2  148.59.48.1  3.357 ms  5.130 ms  3.006 ms

And "route" agrees:
   > route -n get 148.59.48.1
      route to: 148.59.48.1
   destination: 148.59.48.0
	  mask: 255.255.255.192
       gateway: 148.59.4.3
     interface: fxp0
	 flags: <UP,GATEWAY,DONE,PROTO1>
    recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
	  0         0         0         0         0         0      1500         0 

This is not, it should go out 148.59.4.1:
   > traceroute -n 148.59.80.1
   traceroute to 148.59.80.1 (148.59.80.1), 64 hops max, 40 byte packets
    1  139.171.192.26  6.874 ms  6.496 ms  4.288 ms
    2  139.171.198.139  5.907 ms  8.251 ms  4.156 ms
    3  198.22.65.217  5.246 ms  4.961 ms  4.719 ms
    4  198.22.65.222  14.096 ms  4.760 ms  6.545 ms
    5  148.59.80.1  5.753 ms  5.813 ms  5.952 ms


"route" says it should:
   > route -n get 148.59.80.1
      route to: 148.59.80.1
   destination: default
	  mask: default
       gateway: 148.59.4.1
     interface: fxp0
	 flags: <UP,GATEWAY,DONE,STATIC>
    recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
	  0         0         0         0         0         0      1500         0 

netstat -rn (minus a few 148.59.4.x machines that can be ignored)

Internet:
Destination        Gateway            Flags    Refs      Use  Netif Expire
default            148.59.4.1         UGS         0 667619000   fxp0
10.151.89.0/24     link#1             UC          0        0    em0
10.151.89.49       00:c0:9f:21:b2:31  UHLW        1       14    lo0
127.0.0.1          127.0.0.1          UH          2    23811    lo0
148.59.4.0/27      link#2             UC          0        0   fxp0
148.59.4.1         00:a0:c8:2c:5f:38  UHLW        2      602   fxp0     47
148.59.4.3         00:a0:c8:2c:5f:38  UHLW        5        0   fxp0     23
148.59.4.64        ff:ff:ff:ff:ff:ff  UHLWb       1    14991    em0 =>
148.59.4.64/26     link#1             UC          0        0    em0
148.59.4.66        00:02:b3:e9:0e:c0  UHLW        1     8098    em0    903
148.59.4.130       148.59.4.129       UH          0     2073   tun0
148.59.48.0/26     148.59.4.3         UG1         0     1158   fxp0
148.59.50.0/24     148.59.4.3         UG1         0   194507   fxp0
148.59.80.39       148.59.4.3         UGH1        0        0   fxp0
198.11.50.21       148.59.4.3         UGH1        0        0   fxp0
224.0.0.5          127.0.0.1          UGH1        0        0    lo0
224.0.0.6          127.0.0.1          UGH1        0        0    lo0