Significance of the X's on the barn door

I was born in '61, so I was very very young when this show was first actually on the air. I remember it better from the reruns in later years.
What my mom remembers, and I only remember this from her telling me the story, is that we drove by a house in the town in Iowa where I grew up. I was maybe 2 or 3, and I was exclaiming "There's Mr. Ed's house! There's Mr. Ed's house!"
My mom asked me why it was Mr. Ed's house, and I could not give her an explanation. I just knew that it was.
So my mom finally drove my dad by this house, and asked my dad why I thought this was Mr. Ed's house.
My dad recognized it immediately -- the front of the house had these giant white X's on it, just like Mr. Ed's barn! The X's are noticeable in the opening sequence when Mr. Ed opens his door and says "Hello - I'm Mr. Ed." They are noticeable at other times too.
When I graduated from high school, whoever owned this house took the X's down. I would still call it Mr. Ed's house through the years.
I wonder if the Mr. Ed housing development will have houses with a bunch of X's?
On another note, the line from the song (near the end of the song) was always a puzzle to me until I read it in a Mr. Ed book --
"A horse is a horse of course of course
AND THIS ONE WILL TALK TIL HIS VOICE IS HOARSE
you never heard of a talking horse?
Well listen to this --
I AM MR. ED"