deleting an alias from interface cause the static route to be deleted

[Коньков Евгений]

vlan74: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=3<RXCSUM,TXCSUM>
        ether f4:6d:04:7c:7b:d3
        inet6 fe80::f66d:4ff:fe7c:7bd3%vlan74 prefixlen 64 scopeid 0xd
        inet 10.1.26.1 netmask 0xfffffe00 broadcast 10.1.27.255
        inet 10.1.26.3 netmask 0xfffffe00 broadcast 10.1.27.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
        vlan: 74 parent interface: re0

ifconfig vlan74 delete 10.1.26.1

will delete these static routes from route table:

10.3.0.1           10.7.26.2          UGHS        8      367 vlan74
10.1.6.0/23        10.7.26.2          UGS       275   166969 vlan74

Does this a bug?