Transcript:
Charlie Brown stands next to Patty, who is sitting in the chair and reading. He looks at her as she asks,"Charlie Brown, see what time it is, please?"
He walks down the hallway.
He looks at the clock which is sitting on a cabinet with a vase of flowers behind it. He is puzzled.
He smiles and looks up at her with his hands outstretched, holding his right hand slightly higher than his left one. She looks at him and says,"Ten minutes to three? All right, thank you"
The first time Charlie Brown appears in his signature zig-zag shirt.
The gag is recycled from the Li'l Folks strip from June 19, 1949:
So is it canon that Charlie Brown's left arm is shorter than his right arm?
As canon as it gets. His right arm is about 63 pixels from shirt sleeve to fingertip, and his left arm is about 50 pixels. The angle depicted, if anything, would exaggerate the difference