Don't worry about it. Lots of people have their middle name missing from the card, or only a middle initial is there instead of a full middle name, and it doesn't cause problems with traveling or employment or anything else.
EB3 ROW I-485 Approved: July 2007
USC: July 2013
I am a layman, not a lawyer. What I write here is not official or professional legal advice. In addition, my answers on this forum are specific to the scenarios discussed in each thread and should not be generalized to other situations.