Title prorate tax different than the seller actually own

[John Lee]

I purchased the property in October, 2018. Title prorate the tax based on 2017 tax which was only $534.64. I checked the county appraiser, 2018 tax is $1712.76. The seller prorate me only $433.57.  So am I own the county the rest of the property tax? Is this common practice to use previous year and prorate to buyer? Shouldn't the seller pay the tax and I prorate to the seller only for the rest of the year? The sale is closed now, can I ask title or seller to fix this?