Was this private, commercial or CFI? Either way no big deal to fail.
What is a big deal is that you say you were tired after only 2 hours ground and 2 hours flight. In the commercial world in the US, especially fire---(one of the areas you want to get into from reading your previous posts), we frequently work many more hours than this. To give you an example, I have just finished two 14 hour days, flew 7 hours the first and 5 on the second.