D-A-D-D-Y

A couple days ago I showed my boy DADDY on the magna doodle.  I took the magna doodle out today and it was still there.  My smart little guy saw it and pointed to each letter and said D-A-D-D-D-D-D - daddy!

I was like - what?? and asked him to repeat it.  He pointed and said D-A-D-D-Y - daddy.  I asked him to do it a couple more times and he agreed, and then he stopped agreeing.  I may have overdone it.

I've shown him the word daddy a couple times, I guess he got it!  I don't do words very much, but since he loves both vehicles and letters I'll occasionally write BUS or CAR or TRUCK next to the picture he's had me draw of one and talk about what it says.  Does he know any of those words too?

UPDATE 7/13/13
This morning we were playing with crayons and paper and I wrote CAR.  He said each of the letters then took a toy car and put it on the letters and said car.  Since he'd already been holding the car I wasn't sure if he was recognizing the word exactly.
Then I wrote BUS.  He said each letter as I wrote it and then excitedly pointed above the word and said bus! bus! bus!  I said, do you want me to draw a bus?  And he said yes.  I'd say he knows that one!