I flew a practice RNAV10 approach at Oakdale CA the actual inbound course is 084 degrees to ZOSON (FAF) and then 096 to the airport. However my course on my autopilot show 086 and then FAF inbound to the airport it was 098. Checking to see why I had a 2 degree difference in my information. Of course I went to the course button and changed it to 084 but the data wouldn't let me change the course. Does that sound like I have old map data since my charts are current from Seattle avionics data? Any help would be appreciated. Thank you Brent