First of all relax! Go with the flow of date.
If you've been touching throughout the evening, holding hands while walking, laughing, looking into each other eyes, and exchanging flirtatious banter then leaning in for a goodnight kiss at the end of the date will seem (natural). Basically if you both had a wonderful time a kiss just seals the date.
On the other hand if you two have been distant throughout the date, uptight, acting like "stiff robots", having a difficult time keeping a conversation going, and there has not been any (mutual flirting), laughing, touching, then going for a kiss seems way out of line.