Danger signs, or knowing when something isn't right? Well, a guy saying he wants to get alone with you. JUST KIDDING!!
That is up to you. Anything that makes you feel uncomfortable would be a danger sign.
You probably already know this, but I'd like to state it again.
When you meet someone face to face that you met online, it is important to:
* Meet during the day, not at night when its dark.
* Meet in a public, semi-busy place.
* Make sure someone knows exactly where you are at what time. If plans change let that person know.
I used to have a friend "on call". If she called me and I didn't answer the phone then she'd take it to the next level. So someone usually called about an hour or so into the date.

Funny thing about the tips I stated above. When I met Bruce it was during the day at a restaurant for lunch. Then we went to the mall for a while. After that neither of us wanted to go home. So we ended up driving up to Tahoe. Yes, it got dark. Next thing we knew it was 1am!! We stayed the night at his condo. But I refused to go upstairs and sleep in/on a bed so we slept on the couches. LOL He never even kissed me on that (long) date. We still joke about it.

Anyway, if it is the right person you will feel completely comfortable with him. You can be yourself and not feel like you must act a certain way to impress him. Do not sit and wonder why he is talking to you. He is obviously talking to you because he is attracted to you and wants to get to know you.
So just relax, be yourself and enjoy it!!