If you did not prefill the oil filter with oil before installing, then the issue could be air trapped in the oil filter. This happened to me once because I was too lazy to prefill the oil filter. Search the forum and you'll find it has happened to others as well. Solution is to unscrew the oil filter while the bike is running until oil comes out, then tighten back up. This technique is referred to as 'burping' by some here.
Chris Glennon - Portland, OR