This was about 6 months ago when I (M19) first met my girlfriend (F19). Me and her laugh about it now, but I want to get Reddit's opinion on this. We met on Tinder and I took her out on a date to a pizza place I go to frequently. We never met in person before this point.

I tell her to order a pizza and an appetizer if she wanted, and I did the same. The reason for this was because I had a voucher for 50 bucks with of stuff that I wanted to use.

My reasoning behind the Groupon was if the date didn't go well, it wouldn't have been a complete loss, as I wouldn't be stuck with paying full price for a meal of a girl I knew for less than a week. I just like to save money where I can. Luckily, we hit it off very well and the date went off without a hitch. 

I didn't think much of using it at the time, until she told me about it a few weeks ago. She says it was cute but I can't help but to feel embarrassed and stingy, especially considering I had accepted her offer to tip.

Was I the asshole in this situation? Do I need to learn proper Groupon-iquette?