Should I be upset or not? am I being set up for a heart break?

About 5 years ago now I met a girl on Myspace and from there a friendship began. I live on one end of the country and she lives in the other end (literally.) We went from being Myspace friends and it went better when we exchanged cell numbers. We'd talk to each other about everything and anything including love advice, where we'd often joke around on dating each other cause we were so poorly treated. Weeks, months pass and our friendship got better until she had no phone service in which we lost contact for about a year, until she messaged me late last year. Early this year we talked again and caught up and revealed that we got the hots for each other. So that's when we decided to give us a go. We agreed on trying to long distance relationship and in March I purchased plane tickets to go visit her in June and spend the 4th of July together. From Jan to about April we were the best/cutest couple imaginable. Then April came along and I felt a difference in her responses to my text messages, I had an awkward feeling. She went through some life changing experiences (good friend passed away, new apartment) So I was thinking it may be some of that with added stress that caused her mood not to be so lovey dovey. Fast forwarding to June only 3 days now from meeting her in person for the first time she says somethings that brings questions to my head.

She mentioned how she wants to take things slow, she wants to treat this like we're meeting for the first time ever, she doesn't want to rush or force anything but still wants us to be together. She says there's a lot take into consideration (whichi I'm well aware of) she thinks it's best to take it all in steps and meeting before making any permenant decisions, she doesn't want to jump into anything.

My questions are... is this a set up for breaking up? Do I have reason to be upset with this girl? My feelings for her are unconditional. Has she been seeing other guys during this time? What do I do? take this and get upset or be an understanding "nice" guy and do as she says? and perhaps set myself up for another failed relationship?

Since we agreed on being together, I've been the best guy I can possibly be: Very honest, very faithful, very caring, very trusting, very thoughtful and very sweet. I'd get stuff for her and plan on giving them to her as gifts, gifts I know she'd absolutely love... I know how big of a Tim Burton fan she is, so I got her a really cool glow in the dark Nightmare before Xmas poster. Furthermore I waited in a 6 hour line for a Tim Burton signed book, he personally signed it and I took pictures of him, I'm pretty sure she will cherish this book. I've been a great guy to her this whole time.