There may be future gift tax reporting considerations. I can't give you a tutorial on gift taxes, and besides, you shouldn't take tax advice or instruction from an anonymous internet forum poster.
To repeat: If you are asking if there are any tax consequences for you based solely on a 529 account change of ownership from the grandmother to you, the answer is no.
If you don't understand or need further explanation, you need to consult a trusted tax preparer or advisor.