There is nothing prohibiting you from traveling within the United States (and if the possession of marijuana case was in Texas, it was not a class c - it was more likely a class b.)
There is nothing that precludes you from traveling domestically within the U.S. under such circumstance. Make sure you've got a valid picture ID, though.
There "shouldn't" be a problem ... but you never know for sure.
Meet with an immigration attorney.
Franco Capriotti - Senior Immigration Counsel
CAPRIOTTI INTERNATIONAL LAW
firstname.lastname@example.org -- 1-503-803-0055 -- www.capriotti.com
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IMMIGRATION LAW PROFESSOR for 10 years -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.