Self talking. Sure if she is mocking us.

My daughter will become 4 year old coming August. We are staying in Australia for more than 2 years (Exactly after she completed 1 year). She started saying few words after 2.5 years only. She is now learning to communicate both in Tamil (Home) and English (Daycare). Nowadays she is talking in sentences to herself and also do the same when she plays with her toys. For example, if I boil egg she will say to herself - "Amma is boiling egg pappu, come let's eat". This is just an example. She will talk like this for everything. Is that a normal behaviour or do we need to check this further with a doctor. Note: Whenever we ask anything to her, she will be adamant in not giving reply immediately. But ultimately she reply back to us. Also she use to repeat our question knowingly and then gives back the answer. Not sure if she is mocking us.