Did I just throw a tantrum in the store?

I can see SIL (the one I like) needed to get out of the house, since her daily routine was becoming rather redundant. So I asked if she wanted to go shopping at this large baby department store in the city. She agreed, as she was needing some baby items. We packed the children and left on our adventure.

We were throwing items in our carts left and right. They had this fantastic offer on these sleep sacks, buy one get one half. I put two gender neutral size M ones in my cart, as they are thin and will be used for warmer months. Though on the rack that had the BOGO sign, there was only one M. I went over to another rack to pull a M off as they were the same sleeping sack and priced the same. We went on about shopping until we got to the checkout.

The cashier starts scanning my items and then comes across the sleep sacks. As it turns out only one of my sleep sacks qualified for the offer, and the other had not. Excuse me? They're the same item, just a different pattern. She explained that the ones on offer were discontinued prints. That's fine, however I want two size M and there is no more on the offer rack. A 1 year old isn't going to want to be in a sleep sack, it would be silly to buy a large! I kindly asked if her manager would honor the one at half off as there are no more Mediums. The manager declined stating what the cashier told me. Then I was annoyed, but understood and decided against the items because I wasn't getting a deal. I was frustrated and walked back to the register leaving the cashier to speak with the manager. The children were getting restless anyways. It was time to leave. Surprisingly the cashier comes back and says they'll give it to me at half off.

I got a little embarrassed and apologized to the cashier telling her I wasn't arguing with them, or throwing my toys out of the pram. I'm sure the frustration showed on my face, but I didn't kick up a stink to get my way. Lol. She told me it was fine and I wasn't being difficult and understood my stance on getting the correct size. Also, she agreed the signing was confusing for customers since the other rack of sleep sacks 3 feet over aren't on offer. Perhaps, they should be more clear on their advertisements.

Maybe I didn't throw a tantrum then? Lol. I blame it on the hormones.