The same thing happened to me. Freaked out doing the math and trying to figure out where the extra charge was coming from. Talked to several people, made phone calls, talked to bank, called the bank etc. Couldn’t figure it out, made the first higher payment, then the next mortgage payment was back to normal. Concluded that the escrow account was short $600, and instead of the mortgage company saying that, they sent us a $600 increase mortgage bill. Not sure if your situation is the same, but it sounds very similar.