Was I Being Petty???

I went to Walmart today to purchase a few necessities. Apparently Walmart has this new $4 prescription and over the counter drug program and the usually expensive medication that my child is in need of today was on their list. I found the medicine on a big display case that said $4, I was happy and picked it up. I go to check out and it rings up $0.96 higher than advertised. I politely told the cashier that it was supposed to be $4 and she had the slow dude go check the price. In the mean time while she is checking the price I am holding the line up. *biting lip*

Yes, I know I am cheap and I take advantage of every opportunity I have to save some money (pissed to find out gas is $3.42 a gal here and I paid $3.45 a gal where I was at) but I could not help but wonder if I was being petty by holding up this line all over $0.96??? I mean in these times every penny counts, but still.