Yup, exactly that. To me that doesn't seem like it would cause enough fouling to create problems with an in-spec gun unless your cleanings had never touched the extractor or chamber. If these parts had been cleaned, and there was as much fouling as you noted in a prior post within firing only 1000 rounds, then I'd look at something being wrong with the ammo. 1000 rounds of good ammo isn't enough to cause significant fouling, IME.
Maybe a fluke? It shouldn't need a new extractor spring yet, and 1 stoppage in 11,000 rounds doesn't seem indicative of a defective spring either.
God, HKs are
so horrible. Other gun owners have real problems. Here we are trying to figure out why it had one stoppage in 11,000 rounds. **gets a shiver**