Yes they're from 15. Tom may not have tested, or he may have just been lucky. Or processing may have changed a function a bit since he tested. I think I wrote the "hacking a Processing sketch" tutorial last year - I guess there's a date on change log, and the code worked fine then.
The bug only happens on first call to Serial.available (in processing) so could be a number of things that changed I imagine. As I said in my post, it can happen at any time the buffer has NewLine char but no other data.
BTW - it might not be that idea to have more error checking in the routines - but commented out. If there is a noisy serial line (e.g. radios) and a non-numeric char gets through - ParseInts gags.
Please post links to ParseInts source if you know it. The Processing guys apparently like to keep some things secret too.
Paul