The problem with no problem

Question:

When you thank someone for something they've done for you, would you rather hear a response of:
a)  No problem.
b)  No worries.
c)  You're welcome.

I've been hearing a lot of a) no problem lately. Does anyone else have a problem with "no problem"? 

What exactly does that mean?  To me, it says that "it was no problem for me to do what you asked", which leads me to wonder what the response would have been if it *had* been a problem to do what I asked.  If it was a problem, would they have declined to help me?  If it was a problem, would they have let me know that I inconvenienced them?   "No problem" is all about the person who did the good deed and leaves the thanker feeling lucky they received help at all.

b) no worries ... how did that creep into North American usage?  It's a distinctly Australian phrase that sounds strange coming out of the mouths of over-wound North Americans.  Still, it is a better response to a thank you than "no problem"; it says don't worry about it, don't give it another thought.  Still not the greatest response, but better than "you haven't put me out" that "no problem" conveys.

Then there's c) you're welcome.  Now, isn't that a nice response?  It says "I was happy to help you out; you are welcome to my time and efforts.  It was my pleasure to perform that service for you."   It doesn't say anything about the peson who did the favour; it is simply a gracious acknowledgement of a heart-felt thanks.

Obviously, I prefer a nice "you're welcome" ... it is the most gracious response.  I like to hear it when I say thank you to someone, and I like to say it when someone thanks me.  I have a warmer feeling for the person who tells me I'm welcome than for the person who offers that it was no problem to help me. 

Am I being too picky about this?  Should I just be grateful to receive whatever help I've asked for, or a gift I've been given, and assume that the giver of the help or gift was happy to do it, regardless of the words they use?