Renegade,
What is your usual OCI interval before this oil change? As suggested a used oil analysis might help. I've actually extended my OCI from 5,000 KM up to 7,000 KM thanks to a lot of information and knowledge from fellow BITOG'ers.
I also used my oil filter (Bosch Distance plus) for two oil changes which will be around the 12,000 KM mark.
I would say in your case that 4500 to 5000 miles would be the minimum for your OCI.
Regards, JC.