Well, maybe not, but a lot of oil pools in that valley before spilling out the back and being noticeable. So, you're likely driving around with a mini swimming pool of oil on top of your motor.
Further, you don't know the exact mode of failure. There are also plugs which can leak....and IIRC they're bonded/glued, not threaded. I hope BITOG will check me on that. So, if a glued plug is leaking that could potentially blow out or worsen at any time.
I'd need to go back and watch the excellent vid by MCM (Motor City Mechanic) to refresh my memory on all these specifics....but right now I need to keep other information in my brain and can't risk pushing it out with new info (like Kelly Bundy)