We love our Volt outdoor lighting! We completed o...

We love our Volt outdoor lighting! We completed our entire home landscape lighting last year. I was surprised to have a couple of bulbs which should have lasted several years by our calculation, need replaced after 1 year. I asked the question to a Volt about the fact we have had two bulbs expire, but did not get any answer other than they should last for so many hours, etc. It would be nice if someone was able to confirm if these only last 1 year, why are they needing replaced, and should we expect to replace all of them?