How do you Spell "Success?"

Today, Mini-me went peepee in the potty. I put the potty in the kitchen, put my laptop on a bin, and turned on Cars. She has gone several times. But here's my question -- is it normal for her to pee 3 times in an hour? I thought at this stage she should be able to hold it a little longer. I don't want to send her to preschool in the morning in panties if she's just going to go to the bathroom every 20 minutes. By the same token, I don't want to put her back in a diaper and ruin the progress we've made. Suggestions would be appreciated!