It is in the book "Big League Sales Closing Techniques" by Les Dane - it is called "BUY NOW" the goal is to induce in the purchaser the belief that they must "buy now" or the deal will be forever gone ....I strongly urge you to rescind.
Don't worry about losing some offer that is supposedly only available if you buy this offer. The offer you have in hand now can be resurrected if that is what you want. Or, if not, there will be some comparable offer that is available to you. That's part of the sales game that they play - there is always some offer that is available to you only if you buy at that moment - they need to have that to get people to make the final buying decision.
except they will have the same or better "deal" 2, 7 and even 12 weeks from now.
Rescind while you still can