First letter missing

When typing on the Macbook pro late 2013, 50% of the cases the first letter is missing, this primarily happens if I start to type after some pause. I guess it is as if the keyboard goes into some kind of sleep mode and the first type wakes it up but doesn't register the letter. For instance, the first word in the subject was "irst", I had to add the "F" to the beginning of the word. I have found similar issues reported on the internet but none resolved my issue. Am I the only one? is it a hardware problem? thank you