Words vs Phrase

Come X'mas, Jien will be turning 2!!

He has started 'talking' a lot for the last one month or so, mainly nouns ie apple, orange, grape(s), piano, drum, tuba, phone, autie, uncle etc etc.....

Now he started to add a little bit more to his 'phrase' making :

-- Head on (the) pillow..
-- wheel (of) a car
-- many car(s)
-- a big moo(n)!! (he loves watching moon and stars)
-- e(le)phan(t's) trunk

Of late, when we were travelling in our car, he was gazing on something and looked 'blur' and lost, so

I asked, ' Are you ok?'

'I'm fine..!' he answered.

*gulp* It surprises both me and hubby!! Just where/when did he learn to say this? And I wonder if he really knows what it means, hahaha!! :)