Mobs spawning in perfectly lit home. Only after Nether update

Mobs are spawning in  my perfectly lit home. Only after Nether update. Never had one spawn in my house in a year of playing on this survival world, now since the nether update, It seems like light levels aren't relevant to mob spawning somehow. I've had a creeper and three spiders spawn in my house in the last few days of playing. Again, I've thoroughly researched how to light up a house well. And, again, I've never experienced this problem before the recent nether update