Gas light is on but I have full tank (Honda zoomer/ruckus)?

So I got a Honda and today I drove to the gas station before I was driving home. I filled it all up and drove for about 50 minutes when the gas light turned on. I couldn't understand why it did so because I have driven far longer than that without needing gas, so I thought there might be a leak somewhere. So I stopped and checked the tank and it was still a lot of fuel left. I know that the light wasn't supposed to be in when there is so much gas left.

Do you know what could be the reason for why the light is on?

Read more: Gas light is on but I have full tank (Honda zoomer/ruckus)?