That's really weird. I would call A&I and complain. It's been about a year since I used their mailers (I no longer live in the US) but they always did excellent work for me... I never had jagged-edge problems of any kind. I was always very impressed with the quality of the prints from them... you could really tell the difference between well-made colour neg material and the cheap stuff (A&I processing made me fall in love with NPH). I wish I could find a pro lab of that quality here.
I'm sure it was just an oversight on their part. Give them a call and ask.