Rust on transmission

[attrapereves]

There is some rust on the top of my transmission. I'm guessing it was caused by the horrible battery corrosion that happened with the previous owner.

How concerned should I be about this? I made sure to wash the area in baking soda and water.

Tip: When buying a used car, always inspect the car thoroughly, and always do it during the day. I didn't discover the broken radio antenna and battery corrosion until days after I bought the car from the dealer.