PMV-1 Vaccine

[M Kurps]

This may be a stupid question but here it goes, I vaccinated my birds in the spring with the (killed virus)PMV-1 Vaccine. Each time I refilled the syringe I used a clean (new) needle,and held the vaccine upside down. I have some still refrigerated and the expiration date is next year (2010). Now mind you I would let the filled syringe come to room temp. before i vaccinated the birds,and put the vaccine back in the frig as I waited. Now the question is,is the vaccine still good to use, even though your suppose to use the entire contents when you open the vaccine originally.
Thank you in advance.