Possibly pulling your leg, but not necessarily. One thing would be to wonder if there were conversations around that time about his lack of challenge and if those stuck.
Speaking from my own personal experience, starting in K or 1, I decided to try and make things more interesting. I didn't imagine an outside source for changing school like a skip or such. So, I began rushing through everything as my own personal "avoid boredom and be challenged" technique. I had a basic goal of getting only a 90 something on anything and 100 was generally a failure as I had put an unmeasurable amount of extra work into the process. Every test, had to be the first one to turn it in. Certainly didn't help my already wonky handwriting.
Can't say your son has had the same pov, but it is possible. You might be able to probe it past the surface response to see if he has a full inner-working behind that.
As to excuses, well I was also great at appearing to have excuses for everything, to me they were hypotheses and explanations in an attempt to understand why I did what I did or why something didn't work.
