Order could not be submitted at this time error

[foodsleuth]

A customer placed an order last night which went through just fine (was authorized, order confirmation sent) but she saw this error message after the order was placed:
"The order could not be submitted at this time. Please try again later or contact us for assistance."

I checked the authorization server and it did not show any error, no general errors, no declines, etc.

Is there any other condition that would make this error be displayed? I also checked our error log but nothing had been logged either.

Thanks,
Barbara