OP walked right into this one: http://forum.mikrotik.com/t/routeros-bridge-mysteries-explained/147832/1
There can only be one interface into the routing/firewall. vlan-filtering=yes is likely set, so from the Layer3/IPv4 POV, the interface is the VLAN and its IP – the bridge VLAN filtering just forwards it to the VLAN interface at Layer2/Ethernet.