Boundaries with parents and college students?

I'm a sophomore in college, and I'm curious to get input from other parents about what this whole parent/"child" thing should look like now.

Here's the deal:

Yesterday, I lost my cell phone and wasn't able to get it back until this morning. My parents were apparently trying to call/text me, but obviously I didn't get their messages. So my mom Facebook messaged my RA AND another girl from our floor (before trying to contact me via Facebook or e-mail) because she thought maybe I was dead or something. (I had a bad headache the day before, so she was afraid I had a brain aneurysm or something.)

Today when I talked to her, she said she thought it was great that she could talk to my friends on Facebook this year, because last year my RA wasn't real receptive to talking with parents. When I asked what she meant, she said "Well, when we dropped you off on your first day, I tried to leave my name and phone number with Joanne (my RA), and she said that she couldn't do that and you guys were adults." (She apparently thought this was a bad thing; I totally agreed with Joanne!)

So what's your opinion? Where's the balance between being concerned parents and letting go and letting your kids grow up? Because personally, I feel like my mom has violated some boundaries here, but obviously I don't see these things from a parent's perspective.