I use to pump, not breast feed, a year ago. I noticed tonight my boobs were sore so I squeezed one and milk came out, but none from the left. Normal?

Galactorrhea. Expression of milk when not lactating post-partum is suggestive of galactorrhea which has many causes (http://www.Mayoclinic.Com/health/galactorrhea/ds00761) so you need to go see your doctor. We're really concerned for prolactinoma but also need to review your medications and run some simple tests. Be sure to bring in everything you take, even over-the-counter supplements.