rather than accumulate in the bell housing and affect the clutch. However oil leaking out the hole is not normal, a seal is leaking. Have you determined if it is transmission gear lube or engine oil? Smell it, gear oil has a sulfer smell. I assume you have a manual tranny. If auto tranny look for a red color fluid if not too contaminated otherwise a brownish red. If engine oil compare to dip stick sample to determine that oil in leak.