req: Name of 15/16 century Artist/Painting from the Hermitage

[Plym]

I just came back from a visit to St.Petersburg and the Hermitage. And
I'm trying to recollect one painting I really liked. I thought I
rememberd the name and artist, but I can't for the life of me find it
by searching the electronic Hermitage gallery or the web, so I must
have mixed the title/artist with that of another painting. I thought
it was a Giulio Romano painting, named Love Scene (or something like
that), and I really belive it was in one of the Mannerism rooms. But I
might be wrong. Let me describe the painting, and hopefully some of
you know it.

It's a bedroom oil-painting, a man and a woman is laying (almost)
naked in bed, their heads to the left and facing the viewer. To the
right in the doorway an old woman is looking in at the lovers, a smal
dog is jumping/leaning up on the old woman as she stands there with a
grin on her face. Under the lovers bed is a cat. The bed-poles had
some erotic inprints. The paintings caption, I think, described it as
a 15-century painting that was too erotic for its time and wasn't
really exhibited until some hundred years later.

Does anyone know what painting I'm talking about?