IF they were mining with the chips, they wouldn't be so stupid to do it on their own pools or under their own names.
Is it possible to see/track the origins of blocks generated by looking at BlockChain.info?
There was a guy a day or two ago on BFL forums and Reddit claiming that he saw a ton of Blocks coming from Kansas. The accusation coming from the guy on Reddit was that it was BFL using mining hardware.
Edit: Found link, seems BFL deleted the thread?:
http://www.reddit.com/r/Bitcoin/comments/1c1jqd/butterfly_labs_may_be_scamming_us_all/