Looking out the car window

Our conversation riding home from daycare today

Anil: Mommy!
Me: Yes, baby?
Anil: Ayerplin
Me: Hmm?
Anil: Ayerplin!
Me: Airplane?
Anil: Ya!
Anil: Sky!
Me: Yes! Plane in the sky! (smiling - he is just learning about sky)
Anil: Look! Red bus!
Me: Yea! Red bus!
Anil: Red bus sky?
Me: Hmm?
Anil, answering his own question and laughing: No! Red bus ground!

Was that his first joke?