I'm really blown away that a pharmacist would say that... It is standard for multi-use vials to carry a 28 day "beyond use date", meaning that they need to need to be discarded after 28 days once the seal has been punctured!
That would mean every 10ml vial needs to be discarded after 4 weeks? I find that hard to believe since you'd have to take 500mg each week to finish it before 28 days is up. Why would any pharmacy give 10ml vials (which seems to be the standard)?