I worry more when my carboy is not wet when I put wort into it. A wet surface with star san is sanitized. A dry surface, depending on how long it sat and if it was left open to the air may have germs on it.
+1
I like when I rack into a keg filled with Star San and the beer pushes the foam out the top as it fills to the top. It's a good sign that all surfaces have been sanitized.