You will be amazed to see how your child is able to distinguish between uppercase and lowercase letters. Now he has developed the understanding of alphabets and can write apple with a capital A if you ask him to do so. He even knows when to start a sentence with a capital letter. All these are signs of his development in letter recognition.
What you need to know:
You need to keep a check on his notebook and see how he is doing in his school assignments for letter recognition. Make him read things he comes across the house or while travelling. Make it specific to him to identify a capital letter from a word and pronounce it.