If Nodogsplash is installed on an OpenWRT kernel higher then 2.6.26, e.g .28/.30, the intended traffic shaping interface is not sole interface subject to the throttle. There was a short time frame in OpenWRT trunk that had patches for .28 kernel and .30 kernel support to include the ipt_IMQ module. These patches were later dropped and support for xt_IMQ started. While Nodogsplash appears to work perfect with roughly a 2.6.28 kernel and 1.4.1.1 iptables set, when traffic shaping is turned on it actually occurs across all interfaces.
Say for example you have Lan ports or even a VAP on your wireless and you told Nodog to run only on ath0, well all other interfaces end up being slowed down to whatever upload/download speed you have set for the intended interface. This is of course not the desired outcome.
This was tracked to the test imq rules that are created at startup. For some reason, one of the imq test rules in the mangle table couldn't be deleted. Unknown still if this was due to a version of iptables installed.
So a workaround exists at this point by disabling the imq test in /etc/init.d/nodogsplash for that platform.
Just to follow up on this, solution solved the problem with no negative side effects that I see.