I have not heard of any clawback allowance or minimum timeframe on the lease credit. 100% accurate that the dealership does not get paid on the loan origination if pay it off within the first 90 days. You can actually use this as a negotiation tactic by allowing them to mark up the loan in...
In this instance there is NO reason not to lease no matter what the rate/residual is since you can capture the $7500 tax incentive. For those not used to leasing, there is a amortization table just like a loan. Simply buy out the lease the first month.
To answer some questions, no you don't...