Several Starbucks Rewards Members have reported that their reward star points expired before the actual expiration date. Good news is that, one 5 minute phone call will get your points back.
Examples of people’s stars expiring before the expiration date
How to get your expired Starbucks points back
Starbucks is aware of this and this seems to be a common strategy for you to pay a little more. You can simply call 1-800-782-7282 and talk to their customer service and they will not put up a fight. Customer service will just give you back your points and they will expire in another 6 months.