Wow, sure enough, .45 ....
I had actually changed that parameter previously and was attempting to change it back. Although I am not a Mission Planner expert, I was aware that the parameter is in centi-degrees and previous changes to the parameter had returned predictable results. I believe I changed it in the "basic tuning" page and it was very likely a number pad typo. If I did change it in the full parameter list, it was simply an unfortunate brain lapse.
I am ashamed to say that I had totally forgotten that I made that change. I remember now that as I hit "write params" I had received a phone call that I answered and shortly there after realized the plane had not made its turn. I of course dropped the phone as I attempted to remedy the issue. Apparently the the shock of watching the plane fly away dampened my short term memory. I made many small changes that day, but none of them (intentionally) large or drastic, just fine tuning.
Embarrassing, but in the end I'm glad that it was not a FC issue, as that would be more disconcerting.
Apparently I need to stay more focused while flight testing, double check parameter changes and verify flight performance, even when they are not "big" changes.
tridge, thank you very much for your attention to my issue, I still have much to learn.
Stay diligent everyone!