you need an advisor. if you anticipated that when the sale date arose the FMV would be more than what you agreed to sell it for, there could be a gift element involved. The gift tax rules apply to all gifts. the question is whether you made a gift. Even if it is a gift, unless you used up your lifetime exemption of over $12 million there would be no gift tax. another possibility if the rent was above FMV was that you had a rent to buy situation.
