That will happen sometimes. For me, I get immediate crazy swelling, which then goes down, and then it will get red and itchy. But sometimes, if it's not a bad sting, which yours probably wasn't, since she didn't leave the stinger, I'll get just minor swelling or none at all, and then the red and itchy will follow. I've had times where I didn't even know I was stung until a few days later I had a red itchy welt. Every sting is a little bit different.