Why does my puppy wee on the floor!?

My dog does that ALL the time. Whenever I come home, she starts spazzing and jumping on me and gets all excited. xD The last time I entered home, when she started getting excited again, I sort of ignored her and sat on the couch. Then when she went on the couch, I didn't act all energetic, and I pet her normally. After she calmed down, I went back to normal, and nothing happened. She's older now and doesn't do it anymore. Hope I helped you. ^-^