UPDATE
So far not much change. I tried to scrape it off with my finger and I only could get very little off. Has not spread much.
My LFS gave me a plate from one of their tanks that had corraline algae and I introduced it to my tank. About a month later, I got a few pinkish dots on my live rock like you and was a bit concerned. But I believe that was the growth from the coralline algae spores anchoring into the rock and in 3-4 months my rocks started changing to a deeper purplish color. Given that you can barely scrape anything off and it's not spreading, it sounds like corraline algae.
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