Oh really? I lost out on a BOS due to my brew being "slightly under carbonated". It was the only "ding" against it.
How do you know, did you witness the BOS? Generally no notes are kept from the BOS table, at least not in our neck of the woods.
Lower than expected carbonation can cause a whole host of dings - appearance, aroma, flavor and mouthfeel can all be affected. In fact I often serve a nearly flat beer during the BJCP exam and the major flaw, carbonation, is always noted, but many other things can be underwhelming and notable when the carbonation level is too low.
But if that was your only ding I guess you scored a 49 on the score sheet