Pink breast milk from one side

So just to give a background, if it's even relevant at all, I don't pump a lot, only after morning feeds and after my daughter is asleep for the most part. But I've been trying to pump more often especially on my left side because it barely produces anything anymore since my daughter had a pretty early preference. Tonight I decided to put my Lansinoh heat packs on them before pumping which I've only done once or twice before, and when I started pumping I noticed what was coming out of my left breast was clear as water (normally it's more if an opaque white) and then suddenly it turned pink for a minute. I stopped pumping to take this picture. It was really only this much and then returned to normal. My nipple has no cracks or irritation so I know it's not from that. Any idea what could've caused this and is it anything I should be concerned about?