I agree that's fairly large. I've had my gecko do something similar with an upset in digestion. Poor digestion can be caused by a number of things: wrong temperatures, stress from a move or cage change, or parasites.
1. Make certain you have a warm floor surface temperature around 90 F on the warm side. This is best measured with a temp gun, but you can also use a digital temperature monitor with a cable probe and stick the probe to the floor. The gecko needs to be able to lay on a warm floor surface at night to digest food properly.
2. If your gecko continues to have strange poop or generally seems unhealthy, consider having your gecko tested for parasites by a veterinarian.
Let me know if you have any other questions.
For future reference, you'll get more replies if you post in the Leopard Gecko Forum . Just pick whatever sub-forum matches your topic.