Seller wants to increase postage cost after auction has finished and 2 days after I have paid?

[jacks_mummy_2011]

I won a pair of boys school pants on eBay for the starting bidding price of 99 cents + $6.30 postage.

I was the only bidder.

I paid via PayPal on the day that the auction finished then the next day I received this message from the seller: 

"Hi Jessica
I'd like to inform you that despite the postage price recommended by ebay, the cost if postage is $7.60 rather than $6.30. I would greatly appreciate it if you would pay difference of $1.30. Nevertheless, i have posted the item today for you so you will receive it soon.

Kindest regards
Denise"

Am I honestly expected to arrange payment for $1.30 to seller because she incorrectly quoted postage in her listing?

i can't believe that someone would even ask a buyer this, let alone bother for $1:30

Any advice would be greatly appreciated, thanks ☺️