Glad to have helped. You probably were not peaked on 99W, therefore the PBS channels didn't scan, they do require more signal to scan in. As well, there are some people who have been having problems getting them even with dishes larger than yours, so even if you peak the dish, you might not get them. 99W can be a pain!
Strange, but check that your LNB numbers are still correct in your receiver. Hopefully, it was just an anomaly, you will know when you scan in 97W and check the numbers against Lyngsat. You might want to delete some of the transponders that you have scanned in from the other satellites you have been on while scanning them in as 97W, so you know what is new and what are old.