The landlord appears to be taking the position that the new lease constitutes a novation in relation to the last few days of the old lease, such that rent for that period is payable at the new lease rate. That would make sense, perhaps, if the lease ends on 3/31/18, with 12 rent payments over the course of the lease. Without knowing more about what they are thinking, or why they wanted the 3/28 start date, I can only guess about what they're thinking (or if they're thinking). I personally don't know why the landlord is quibbling over $2, but if it were me I value my time above and beyond the $2 it will take to make the issue go away.

