It's so Safe Here in my Cacoon

I am an introvert.  Introverts can be misunderstood.  We are perceived as being snobby or unapproachable.   Being an introvert can be a challenge, especially at work.  I am a "go to" person.  This probably isn't the best positon for an introvert.  Admittedly, I don't cope well with interruptions.  When I am deep in thought, it takes me a couple of moments to avert my attention.  It is jarring.  Hence, I'm generally not all perky and smiley and it's not well received by the person interrupting me.  This has been the topic of my reviews for many years.  I feel like it's a form of discrimination.  I wonder, do extroverts get chastised for their gregarious behavior? 

This past Monday I was on vacation.  Other than visiting with my family on Saturday, I was alone with my thoughts for the remainder of the weekend.  I'm always stunned when I have to return to work after the weekend.  It's hard to adapt to the invasion of people into my personal space.  My collegue noticed how quiet I was and on Thursday came by to retrieve something from the printer.  He says to me"your not as quiet as you were on Tuesday, things must be better".  I explain to him that because I'm an introvert, returning to work after the weekend is always difficult. I just want to retreat like a turtle into it's shell instead of transitioning to this customer service personna.  He says "ok, I won't invade your shell".   Now I feel bad.  I hope I didn't offend him. It's not that I didn't want to socialize and want to alienate myself from everyone.  I just need more time than the average bear to mingle.