Escrow shortage amount?

Received my Annual Escrow Account Disclosure Statement, purchased home on 12/1/2010 being a first time home buyer I am new to this, after doing some research (RESPA) I understand now why they do this on an Escrow account although it would have been nice to know this before hand and be prepared for a payment increase my agent or the loan officer could have given me a heads up, but of course they wont, in fear that people would probably back out o.k. that's something I have to deal with... However! what I don't understand is that at the bottom of my Disclosure Statement there is a Lump-Sum Escrow shortage Payment Coupon for the amount of $4,149.40 and of course I have 2 options, they break it down in payments and add it to my monthly or I can pay the lump sum. Can anyone please explain what happened here??