Am i being taken advantage of with insurance?

[Sasha Fukuda]

So, i bought a triplex in Keene, NH in March of this year. This is my first property, so it's all very new to me. My insurance agent gave me a great quote on the house that was cheaper than all the competitors. I ended up prepaying for one year's worth of insurance, and my lender escrowed 2 months worth of insurance on top of that. I also put more money into escrow every month. Now, a couple months after i bought the property, I wonder if this is excessive. Why do they need 14 months of insurance plus a monthly escrow? I recently found out that a different lender (TD Bank) doesn't escrow for insurance at all, so now i'm really wondering if i made a mistake. 

In addition to that, my insurance agent recently sent me an email saying that after sending an inspector to my property, they've decided that their estimate of my house's replacement cost is really $527,000. Their previous quote was $413,000, which is over $100,000 less/ roughly 20% less. I'm wondering how they could be off by so much? Now they want me to sign a statement agreeing to the increase after i've already pre paid based on the $413k quote. I'd only have to pay $20 more a month, so the actual cost to me isn't that big of a deal. However, i can't help but feel as if i've been misled. I wonder if they deliberately underquoted me so that i'd choose their policy over their competitors? 

Do you think i'm overreacting to the new estimate? Would you sign the document if you were me? Is 14 months of insurance prepay/ escrow plus a monthly escrow reasonable to begin with?