Closing Question - Heating Oil

[Nick Noon]

So I am closing on my first property tomorrow.  I got a good deal on it and am hoping to get some sweat equity when I'm done rehabbing it.  I bought the house "as-is".  When I did the final walkthrough today, my RE agent said I should bring my checkbook to closing, mostly because I am to pay for the heating oil in the oil tank they just filled up.  Unfortunately, one of the first things I'm doing to the house is ripping out the oil tank and putting in a gas furnace.  I don't feel as though as I should have to pay for the oil as I did not ask for this and I bought the house as-is.  

It's a nice gesture on the sellers part but I don't think I should have to pick up the $600+/- Bill for something I did not ask for.  My RE agent said this is "typical" for the seller to fill the oil tank before closing and the buyer paying for it.  Both my RE agent and seller knew I was rehabbing the property as I am doing a 203k loan.

What should I do at closing tomorrow?  I don't want to pay for the oil