My doctor said that an avm was accidentally found in my mri but i don't have to worry about it..should i seek a 2nd opinion?

It depends: on the type of vascular malformation. Certain types are generally small, incidentally discovered lesions that require no treatment. Other types may require intervention and/or closer follow up due to the propensity to bleed. It sounds like you have the former rather than the latter, but ask your doctor to explain if you have worries. A second opinion can be helpful if you are still uncomfortable