It's pretty simple, when  two people really want to make a long distance relationship work, they work at it together and understand how small things can get blown out of proportion. If this was a one time occurrence, I would dismiss it, but it seems pretty consistent based on what you said. 

PS. Instead of trying to think about what she might be upto, why don't you muster up the guts and ask her exactly what you asked us. It'll save you a lot of headache and heartache. See what she says, and decide if she's still worth it.