Kinda hard to tell from the photo but to me that doesn't look like pink fluid so must as rust. Lots of things in and around AC's (especially the plastic covers and support frames) are held on with screws with no protection beyond some thin paint. It's easy to scratch and it doesn't take long to rust especially in wet or salty climates.
I would clean that area really well with some Clorox Cleanup and/or Simple Green (spray, let sit 5 mins, then rinse really well) and wait a few days, running the A/C as much as you can, then check again.