I wouldn't doubt it at all. You never know.
If McCann is telling the truth a similar thing happened to Mike Williams during the season. He blew under the legal limit and THEN they suspected he was under the influence of something else so they asked him to do a urinalysis and he said he had nothing to hide so he did it. When they got the results back it showed he was completely clean. Charges were dropped, but the damage was already done via media.