I have gotten very bad looks for nursing my baby in public? Does this happen to you often?

With my first daughter i have never gotten any rude looks or rude comments, i breastfed her until she was 16months when she then self weaned. I have 8month old twins who i breastfed and i pump and yesterday when me and my husband went to the mall we let our 4yo play at the play place and while he bottle fed(the pumped milk) to one of the girls and i breastfed the other. This women came up to me and made the comment that my baby was WAY to big to still be breastfeeding and either way it should be done at home. I was pretty insulted to be honest. I wasn't all out in the open about it. Does other breastfeeding mother has or have had this problem? Is this just common?