There is a reason why programming chops are not usually measured in lines of code.
In my opinion the "art" of programming is to keep things simple yet still solve the complex problems.
I'd say the guy was being humble for sure, as it seems extremely unlikely he would have the discipline to sit down and write something SIMPLE from scratch if he really was a bad programmer.
"I'm not smart enough to understand this really complicated code, so I decided to write something smaller and simpler."
This is something a co-worker of mine said once.