As I dismounted from my bike it fell over onto its left side because I thought the kickstand was set when it really wasn't. When I picked it back up, I noticed what appeared to be a small pool of oil on the concrete driveway. I looked under the bike and there appears to be a small hole under the engine case that the fluid seems to be leaking from. Strangely, the hole appears to be machined and without threads.

Does anyone know what the hole is for and what the fluid might have been? I checked my oil and it is still full. I attached a pic of the hole.

Thank you!