Question about renting a room and security deposit. (lease, landlord)

[PWNT]

Please bear with me :

I went to see a room on the last day of the month to move-in on the 15th, like they do in NYC in some cases. They wanted the room to be rented immediately, but they were willing to negotiate. I was interested in the room, and to demonstrate interest (which I explicitly stated that there was no commitment until I sign a lease) I gave a post-dated check to the leaseholder for a week later.

What the leaseholder's friend (the leaseholder was not present) and I agreed on was that as long as I don't get to sign a document stating the rent of the room and the conditions of the agreement, there is no deal, and that the deal (including the check that was intended to demonstrate interest only, and no type of commitment to a lease) would be canceled if there was no signing. Hence, the check was post-dated to give enough time to place a stop-payment if the deal didn't occur. The leaseholder's friend was aware of this when I gave him a post-dated check, which he gladly accepted at the time. We scheduled a later date during the week to sign a document making things official.

I talked to my landlord the next day, told him I was moving out, and he decided to give me a better deal on my current lease, which I agreed to and signed on it after I informed the other person (leaseholder's friend) about my decision that same day. He demonstrated disappointment and told me that I wasted his time. I apologized for the situation and moved on. I canceled (stop payment) the check that same day.

The leaseholder emailed me later in the week, stating that my actions where unethical, that they lost money because of me, and that my word means nothing. I decided not to answer in order not to fuel any fire, and because I never came in any type of contact with the leaseholder.

My question is: Can they sue and win because they claim that I made a deal with them and use the check as evidence?