Hi Ben,
How do you re-confirm them? There are definitely cases where SSID/Security is the same but each AP has its own DHCP server and roaming between them will require getting a new DHCP address (onthe same (NAT'd) subnet and with same gateway, likely as not).
Using DHCPREQUEST to verify obtained parameters, or the DHCPv6 equivalent Confirm message. This obviously requires some integration between the dhcp daemon and the supplicant.
Regards, -Denis