What does a girl mean when she says "you did nothing wrong"

Anonymous
my girlfriend and I have been together for almost 5 months. and we have been just fine up til now. now we have been talking through the phone and text til she broke her phone a little while ago. so we have been talking through aim while she is on her comp and I'm on my cell. and today we have been talking right, everything is going good til I didn't send anything back for like 2 mins. now my phone does take a little while to send and receive messages through aim mobile. and after that 20 min period of silence I sent something back and she got mad. so I apologize for not sending anything within that time period of silence. and she kept saying its ok its ok just shut up. you did nothing wrong. now what I want to know is she mad at me for what I did or is she mad at something else entirely separate? I need some help.
Updates
+1 y
if she's mad about something else should I call her or aim her and ask her whats the matter? OR if she's mad at me should I bring it up to her when I call her or aim her or should I just drop it and move on?
What does a girl mean when she says "you did nothing wrong"
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