Flaws in the casting that may not be actual cracks.
If someone is doing an oil/filter change, maybe they could take a close look at their cover and let us know what it looks like. Posting a photo would help.It looks like only 1 of the cracks lines up with an oil filter cover bolt, The others are running off of indentations in the casting. Plus I find it VERY hard to believe that the notoriously brittle oil filter cover bolts would come even close to doing that kind of damage to the side cover without snapping off well before from being over-tightened. Those things routinely break just from using a torque wrench.
I wonder how many of us may have the same "flaw" in our side covers to varying degrees without really noticing it yet. I know I'm going to look closer on my next oil change. For all we know it could be a known issue at Honda, maybe cosmetic only and still well within tolerances for safe operation of the engine.
I hope the OP follows up with whatever info he can wrest from Honda. This "issue" really has me curious.