Today I heard someone saying "I too am okay", after that guy asked "how are you" and other person replied "I'm okay, how about you?"
This was the first time that I heard this and wondering whether this is a correct sentence or not.
It is technically correct, even though the word order would suggest poetry rather than everyday speech. Some of the variants would include:
I'm okay too. Thank you.
So am I. Thanks.
It's grammatically correct and the meaning makes sense too. However, it's not commonly used.
"I, too, am ok." This could mean that the speaker knows of at least one other person who is ok. "I am ok, too." This could mean that the speaker feels ok, even though she/he feels something else as well. Example (after an accident): "I'm shaken up, but I am ok, too."
This makes sense grammatically as it is stating that the second person feels the same way as the first person. Such as when you say, "I am hungry," and someone answers, "I too am hungry." This is not often used in spoken vernacular, but it is grammatically correct and makes sense.