38 days before the end of my 12 mo. lease I rec'd a reminder to renew or provide notice to vacate.I gave notice, now theyre trying to charge 1 mo rent

To answer this question, you need to look to the lease itself.  It should identify what minimum notice you need to give and identify renewal terms (for instance, the lease could renew automatically or did you need to take steps to renew it).

One good resource in this state for tenant questions is the non-profit Baltimore Neighborhoods, Inc. - you might want to check out their website or call their hotline to get general information.  If you still have questions, you are encouraged to hire a lawyer to review your lease, the letter and any bill for additional rental.