Yes, it is possible that the landlord is attempting to catch up on missed mortgage payments. However, without him showing you proof of this, there is no other way I know for you to find out. If the bankruptcy was dismissed, then the bankruptcy has nothing to do with the mortgage anymore.
The term "surrender" may or may not have any meaning at all in a case that is dismissed ("backed out" is not a proper term for anything in Bankruptcy). It is a bankruptcy term that means he will allow the lender to foreclose. If the lender does not foreclose and the case is dismissed, his intent to surrender is meaningless. The lender may or may not foreclose because of a default in payments or other reasons.
Since your landlord's Ch.13 was dismissed (probably for failure to make Plan payments), he can keep the property until it is foreclosed upon. Sounds like he wants to keep it, so he is making monthly mortgage payments.
Be sure to designate "best answer." If you live in Oregon, you may call me for more detailed advice, 503-650-9662. Please be aware that each answer on this website is based upon the facts, or lack thereof, provided in the question. To be sure you get complete and comprehensive answers, based upon the totality of your situation, contact a local attorney who specializes in the area of law that involves your legal problem. Diane L. Gruber has been practicing law in Oregon for 26 years, specializing in family law, bankruptcy, estate planning and probate. Note: Diane L. Gruber does not represent you until a written fee agreement has been signed by you and Diane L. Gruber, and the fee listed in the agreement has been paid.