I don't remember what this is called anymore (it's been months since I read the guides on this site) but it sounds like you did a technique where you wake up and re-enter the dream fairly quickly and with relative ease. This is easiest to replicate if you stay as still as possible when you wake up, and then focus on the dreamscape that you would like to enter and let yourself drift into it. The key is staying still so that your body thinks you're still dreaming.