This just happened to my step daughter last night 12-03-2008. I not sure I should say it was the Whistler, but then we are claiming anything happening here, is him in his prankish style.
So far she had not had an experience from him. That night she was reading her book in the living room on the love seat, with the TV on. My wife was in the kitchen, the boy was practicing his guitar in his bedroom, and I was in the basement on the computer. She is into reading Vampire books right now, and was reading one at the moment with the cat by her side on the couch that does not rock.
She closed her book to get up to go to her computer, when the couch started shaking. It was not a violent shake to her, but one to get you to notice that it was unreal. Both she and the cat jumped off in shock. She saw nothing shaking it, but it shook, and then quit after she got off and ran to the kitchen to tell her Mom. Then they both rushed downstairs to let me know.
We do not live in an active earthquake system or fault here in Minnesota, at least not an active one. But if that were so there would be more than the love seat rocking, and the cat did not like what was going on either. Possibly a brief visit from our frequent visitor?