Mysterious Mystifying Mystery

The picture above my desk, that my sister painted, is tilted slightly to the left this morning. It wasn't tilted like that yesterday. We haven't had an earthquake. I didn't bump it. So, what happened?
I can come up with only one logical explanation. Yesterday was the 92nd anniversary of my dad's birthday. (He died 10 years ago.) But here's the deal: He was a staunch Republican. My sister and I are staunch anti-Republicans. I figure that his spirit stopped by my desk last night and deliberately tilted the picture - TO THE LEFT - as a reminder that my left-leaning political viewpoint is askew. He could be kind-of passive/aggressive like that.
On the other hand, maybe our house is sinking into the bay. In which case, the picture is straight and the house is tilted!