@RR: you might be talking about earlier cracking in a different aircraft - you mention that the aircraft was flown after adressing minor cracking. The F-35C that I'm referencing is a test article as mentioned in DOT&E written testimony to Congress last week:
"Structural testing. Major findings are continuing in the durability test articles, particularly in the titanium bulkhead in the F-35C test article. Significant limitations to the life of the fielded F-35C aircraft can only be addressed with intrusive structural modifications prior to the expected full service life, and show again the high cost of concurrent production and development. In the past year, discoveries of unpredicted cracks continued to occur, and in some cases required pauses in testing to determine root causes and fixes. This occurred in all three variants. Currently, only the F-35A structural test article can be tested; it is about to begin the third lifetime test phase, or the third series of 8,000 equivalent flight hours of testing. The F-35B test article is still down for repairs needed to complete the second lifetime. The F-35C test article restarted testing in mid-February but stopped three days later when strain gauges indicated cracking in a titanium bulkhead; it has not yet restarted."