I would wait a day or so. Paypal allows you plenty of time to contact the buyer and try to resolve the issue before escalating to filing a claim.

This has happened to me before as well and I jumped the gun. Needless to say, the buyer hadn't had a chance to respond and he ended up making things right. It's funny that my situation was identical to yours! Be patient but diligent until it's resolved.

Good Luck.