Hi all

I have had 2 experiences lately that make me feel as though when I say thanks, but its really not needed that people don't think I am serious or worry I am upset anyhow... let me give you the experience.
1. I was at Starbucks yesterday ordering myself a mocha and my SO (who was still at work so he needed it!) a drink as well. Apparently the cashier misheard me, or I mispoke, or whatever and when my Venti Skim Mocha came out it was in fact and *iced* drink though I had ordered a hot. Since there were other people around I didn't realize it was mine and kept waiting (5 minutes, max). When it was clear of other people they asked me what I was waiting for and I let them know, and they said the iced drink was mine.
So I took the iced mocha not caring all too much and the barista apoligized profusely but I laughed it off and let her know I'd never tried and iced and I might like it even more (and actually I do). However she wouldn't let it go and offered me a gift card (I said no thank you, its not a big deal REALLY). Well apparently she has slipped the gift card for a free drink in my pocket while I was fiddling with my drinks. I don't want to seem like a grumbly customer. I wasn't unhappy and definetly not upset. Come on, I got a drink mostly correct, who cares?
2. Me and SO were eating dinner at a nicer restuarant. We ate, we paid, we left a tip and went home. 2 days later I was looking at my bank account online and noticed that only the money for the actual bill was taken out of the account but not the tip I left (almost 20 bucks so probably not insignificant for the server, I have been there myself!). So on my lunch hour I dropped by the place with my copy of the reciept and let them know about the mistake. It turns out the server had lost the signed copy so couldn't get his tip, but when I came back he would be able to get it. So we were all happy. However, the manager wanted to give me something for my "trouble" and even though I again told him it wasn't necessary he gave me a certificate for an amount that means free dinner/bottle of wine!
Are most customers in this world so out of control and mean towards managements and even the smallest of infractions that this is just what is done? Could I have somehow given the impression that I was upset? Should I just take everything offered to me even though I am not an unhappy customer or disgruntled in anyway?
I hope this doesn't sound stupid. I can understand wanting to make an unhappy customer happy. But I am a happy customer, I don't want to give the impression I'm not and freebies are necessary for me to return.

Thanks all-