I feel like I have flirted with another girl?

Me and my girlfriend have been dating for a little under a year now and things are going pretty good. But recently I did something that I fear might have been wrong and I feel really guilty about it.

I was playing a game on my iPhone called Draw Something, some people might have heard of it. With every drawing you send to a person you can attach a message to it. I was playing with some random girl from america and a few messages were exchanged about usual things like where do you live, but nothing much. Then randomly she sent the message "do you have a cell phone number?". As soon as I read that I knew that there wasn't a chance in hell that I was sending any random girl my phone number for obvious reasons - I have a girlfriend. Looking back I should have just said that's innappropriate, or just deleted her from my game list, but I wrote "Yeah, why? XD". I know I wrote it just to see what she was going to say back. If she had asked for it, I was going to respond with either no I have a girlfriend, or I would just leave the game. So i sent the message saying "Yeah, why?". Then about 12 hours later I went onto the game and deleted her off it before she sent anything back because I felt like I shouldn't have asked that.

Even though I just sent that message to see what it was she was going to say or ask back I feel like I somewhat flirted or something? Maybe I just liked the attention I don't know, but I was never going to give out my number.

I feel guilty… Any opinions on the situation?

I'm glad you're concerned about your relationship. That's really good.
In my opinion, simply asking why she wanted your number isn't flirting. It's just a simple question; it's not necessarily flirting unless you meant it to be. At least you don't have to confront this odd girl again.

Bro your good man as long as you didn't cheat or anything like that if want tell your girl friend how you feel guilty if she's cool she'll laugh and say I cute and sweet you are about feeling guilty but yea it's all good in my opinion

You're a really good person.
Second, you shouldn't worry about it. It doesn't mean she wanted to date you or have you cheat on your girlfriend with her. It's like having another friend that's a girl.
You shouldn't feel guilty. Nothing happened, and nothing might've. Don't worry about it, okay?

Don't feel guilty although you maybe shouldn't even be talking to other girls what you never did was give out your number so i don't think you did anything wrong… Breathe you're a good guy for even questioning yourself.