By law, vaccines need to be marked with an expiration date....what I was told was that the effectiveness will diminish slightly over time....that you will need to revaccinate promptly if you use them....
when I worked at Penn Vet, I had a friend with 20+ "barn cats" (who would most definitely gravitate to the house when ever they felt like it!) A clinician there whose wife had a small animal clinic gave me a whole box or two of expired vaccines and said to use them up on the barn cats....they were fine, they were effective and they would not use them up in the practice....I would not worry about the vaccine, but I would be annoyed at the vet for not keeping fresh stock on hand and using expired stock on a paying customer....just on GP!!!
Csabre Sch1, Hexe Sch2, SG Bengal, Lynx, Komet, Kira HGH & Kougar v Wolfstraum ~ Ziberia IPO1 ~ ATB Basha, Kougar & Kyra, Fenja, Sch3s, Cito, Sch2, Danger RH & Alice Sch1s ~Kelsey