Is it normal that i how i come across is different than how i feel

I have recently discovered that the impression I seem to give people is completely different from how I personally feel or imagine I give people.

Even though I have plenty of friends who seem to like me for who I am, on numerous occasions I have been told that at first glance I come across as rude, egocentrical and/or basically act like a dickhead.

Personally I consider myself kind of insecure, and I admit that I do not feel like I am a very outgoing person in general, but I do not see myself as overly negative or self-absorbed.

However, whenever I meet new people they (later-on) tell me that I come across as sarcastic and arrogant.

This kind of confuses me, because I have nothing to be arrogant about, and I certainly do not try to be sarcastic.

So I was wondering if you ever feel misjudged by people around you, or do I really need to adapt my attitude to better reflect my personality?