Creeper Server Spawning Bug

Creepers kept spawning in rooms that were fully lit up and the longest we could go was 50 seconds without a creeper even in the daytime

What I expected to happen was
That the creepers wouldn't spawn because it was the right amount of lighting

What actually happened was
That the creepers did spawn and normally spawned about 2 blocks away from me

I don't know how to reproduce this bug but as I quit out then it was finez