InfoPath 2007 - Design Checker Error "Binding a non-repeating control to a repeating field or group is not supported by InfoPath Forms Services."

For read-only purposes, I had expression boxes in my InfoPath 2007 form (browser-enabled) that referred to (via XPath) repeating items within the form - but using an XPath sum(). Even though sum always returns a single value, InfoPath (erroneously) detects the use of the repeating table (i.e. I am trying to sum the total purchase order items). It then shows the following error in the Design Checker:

Binding a non-repeating control to a repeating field or group is not supported by InfoPath Forms Services. To fix this problem, remove the control or replace it with a repeating control, such as repeating section or table."

I automatically assumed that this would be the same as other "errors" and would prevent the publication and activation of this form. This is not the case. In fact, the Design Checker should really should show as a warning, as you can safely ignore the "error" and publish anyway.