I am 45 and have had my tubes tied for over 15 years. My husband has also had a vasectomy. My last period showed no signs and I only spotted for 2 days and it was very light. What does this mean?

It's possible that you are starting perimenopause, which can go on for several years. Often irregular bleeding is an early indication. Some women will have increased bleeding, some unusually light bleeding, and bleeding may occur more frequently or start to be infrequent.
It may just be an off cycle.

See what happens when the next period is due. If it too is different from your norm, you could see your gyn.