Tepe,
I think it may be tough for her to add the sorbate now that it is bottled, not just racked.
Nevertheless, my advice also is to relax - sorbate is a valuable preservative, but is not absolutely necessary to making and having a good wine. It prevents/inhibits growth of some bad stuff after bottling, which is why it so widely used as a food preservative. As long as you got your K-meta in there and aren't planning on aging the wine for 5+ years, you should be fine. Don't sweat it - wine is remarkably good at taking care of itself. It's also happy to get all the TLC it can, however.
Bart