Legally, yes, if you're dealing with a sane, professionally run company.
You're dealing with a tar pit of con artists who have time and again expressed open contempt for writers and positively loathe the ones who try to break free. The people at the top are narcissistic sociopaths with no sense of right or wrong. If they can get away with something, they will, and childish tit-for-tat schoolyard bully behavior is their norm.
I'd follow up with a SASE requesting a written formal statement that your rights are reverted on whatever date is on the contract.
You might put in that you absolutely need a statement from them for your tax statement. It can't hurt.
Or mention -- if that doesn't work -- that if they don't reply with the statement that you'll have to bring it to the attention of the Maryland attorney general's office of consumer affairs.
You are a consumer seeking a small business courtesy that can be resolved by a single statement in less than a minute, not asking them to dig a new Panama Canal with their collective out-of-joint noses.
Though the latter is a cheering image.
Gillhoughly, I do enjoy reading your posts. Your wit almost always makes me laugh.
It might also work to just threaten to keep sending them letters until they respond. They don't like being bothered by writers they can't make any money off of.