a) I would have been late for the training
b) I wouldn’t have the chance to eat at all
c) There’s no saying that the same customers would still be there
it sounded from the way you wrote it that you had this thought right after leaving the store (though you didnt actually say that)
but in any case if you really were concerned that you had caused a chillul Hashem then your reasons a and b should of little or no consideration
and even reason c is of little consequence if you actually felt this was a potential chillul Hashem, as some or all might still have been there.