I don't think your model year has the auto-tensioner set-up on the primary chain ('06?). So if you have the inspection window in the primary cover, open that and check. If it needs adjustment, loosen it first so you can lift the chain to see what condition the shoe is in, then adjust it as specified in the book.
You may want to change out the fluid in the primary. I suggest HD's Formula + or Spectro Primary Chaincase lube.
If the chain was not loose, and changing out the fluid DOES NOT solve the problem, you may have to pop off the primary cover to check the torque on the compensator nut. Do this soon, as the consequences to letting it back off any amount are expensive.
TQ