Seeing this error message only when selecting the in store selection which is set at the default level of $0.00. If flat rate shipping is chosen no warnings and all works well.
* warning: call_user_func(): First argument is expected to be a valid callback in C:\apache2triad\htdocs\drupal_5.2\modules\shipping\uc_quote\uc_quote.module on line 875.
* Invalid option selected. Recalculate shipping quotes to continue.
Reinstalled the modules in question. See the same issue on the localhost site (Drupal 5.2) and two live sites (Drupal 5.3).