When you meet the right person, you usually do know it. It could only be one date, but there is something different about them. Don't rush in though, they could take down their wall and you might not like them after all. Take your time and enjoy the relationship.
Your only out of line if you are in a relationship with someone else. If you are in a bad relationship leave that person and go on with your life with the other guy that is making you feel on top of the world!