Usually I try that with girls I'm interested in. But if they're friends and I know they've been feeling really bad about themselves and their looks, I will compliment them and call them "gorgeous."
Usually I reserve "beautiful" for girls that I really think ARE beautiful. If I'm angry with you, or I don't want to talk with you, and you've been on my case A LOT, then I purposely stop calling girls beautiful.
If I'm mad at you, but I love you, you'll probably still get a "beautiful" in there as a nickname. But the longer we're arguing and fighting, over little things, and the more I see really bad behavior, the less likely I am to still want to be around, calling you sweet names.
So, it could mean something, or it could just be a generic hello with a little flirt in there. Hard to tell.
Definitely sounds like it means something, for him to do it out of the blue is something, or even at all for that matter. The text he gave you is a bit vague, perhaps with a different motive behind it, it's too hard to tell since it was so random. The hey part is generic, nothing attatched to it. I think it's a bit funny you're so love-struck you're trying to figure out what hey means. Oh well, he had to say something before beautiful didn't he? You're going crazy over this, but it's only natural. Don't worry about it, just try to contact him and see what's going on.
Well, there might be something there, and there might not. Most of my guyfriends greet me with "hey babe" "hey beautiful" or even "hey hottie" which is a little weird, but normal to them I guess. Enjoy it! Maybe reply with "what's up, stud?" :P should be good!