Contradiction?

I was recently watching the episode in which the Costanzas decide to move to Del Boca Vista. (By the way, what is this one called?) Anyway, in it, Frank showed Kramer the Costanzas' bedroom, which had two separate (twin) beds for Frank and Estelle. He (Frank) said they decided 30 years ago to sleep separately. This is inconsistent, because in The Cigar Store Indian, when George invites a woman over and pretends it's his house, Estelle yelled "You had sex in our bed!" and George says it's because his bed is too small. Anybody else notice the contradiction?