Your Garmin help, please

OK so overnight I took the following steps:

• Factory reset the Edge Touring unit
  
• Updated the maps via Garmin Express (maps installed on SD card)
  
• Re-downloaded fresh courses from ridewithgps.com and exported .GPX (track) files
  
• Copied the .gpx files to the garmin device memory (not SD)
  
  

This morning's commute, I turned the Garmin on and it automatically found a course - as one of the .gpx files I exported was "home to work". As I was cycling it was giving me turn-by-turn prompts, however, STILL 35-40 ft off. As I'm approaching a road it's still telling me I've got 35-40 ft left before the turn.

Any further suggestions?