oil looking stuff in milk

brideinsummer04

DS wouldn't take much of his morning bottle while I was at work today. DH was wondering if the BM was bad. He kept what was left of it and showed me how it looked after defrosting today. It looked like yellowish orangish oil sitting on top of the milk. I've seen cream looking stuff on top before but not oil looking stuff. Why does it look like oil and does that mean the milk is bad? Thanks in advance for your help!