Some places that offer free shipping only offer it on certain items also.
I had a similar shipping issue a few months ago. It was not a free shipping issue but was a paid for shipping issue. I recently bought a new tractor. A few days after I got the tractor I decided to order the factory service manual so I called the selling dealer to place the order for me. He called me back and said I had to pre-pay for the manual. He gave me the price and said he'd have to add the shipping cost. I thought OK, that way I wouldn't have to make a trip to pick it up and gave him my CC#. He already had my mailing address. I waited about 10 days and no manual arrived so I called the dealer to check the status of my order. He did and said it was shipped. The next day he calls and said my service manual had arrived at his store. I asked why it was there since I paid for the manual including shipping it should have been shipped to me. He said that the shipping cost I paid was to him not me. My blood pressure hit the roof. He said he could send it to me but would have to charge me shipping (again). The reason I ordered it and paid for shipping was so I didn't have to make a 90 mile trip (45 miles each way) to the dealership to get it.
This dealer also does not offer any LS items (hats, shirts, coffee cups, etc.) either. Needless to say, He is NOT my dealer any longer. I now have several other dealers to buy parts from.