When my bike had 40K miles, I experienced the fluctuating oil pressure you are describing. The fluctuations were unaccompanied by any change in engine noise or anything else--just a fluctuating oil pressure gauge. And the fluctuations occurred with no apparent pattern. I rode the bike like that for at least 1K miles.
As I was planning a cam change, I had the dealership open the cam chest with the agreement that if the cam chain tensioners were shot, they'd cover the the parts and labor under the extended service plan, and I'd pay a modest labor charge for pressing in the new cams. If no problem with the tensioners, I'd pay the full parts and labor charge.
The tensioners were shot and those and the oil pump were replaced under the extended service plan for the $50 deductible.
Hope your experience is different from mine, but I'd check the cam chain tensioners.
Carl
