Unfortunate they ruled against you without the buyer even providing proof of any kind, really do hope it comes back perfect condition make sure you record yourself opening the box when it arrives incase its damaged or anything.
A friend of mine had a PP dispute where it was a similar thing, the buyer found some 'problem' with it after arrived, even though no problem existed. The buyer was not forced to provide any proof that things were not what he expected, and my friend had to issue a refund. When he got the item back it, the buyer had damaged it - he cut a peice of it off, there was no way this happened in transit, and was not the issue he claimed was the problem.
My friend called PP back to complain and basically their response was, sorry, your problem now. So even if it was damaged now, the outcome probably won't change. PP/eBay is a buyers dream.