Hi and Welcome!
It's not at all a stupid question. I wish more newbies would ask. Yes, it should go away, but for some it never does. It helps if you're not vaping something that looks like a cigarette. You have to get over the idea that you're smoking. Some people have a hard time with that and feel like they're doing something wrong and vape in the smoking areas and generally sneak around. That convinces people that vaping is just like smoking, and we vapers don't need that.
Most people will just be curious, especially if they don't think they know what you're doing (again, a non-cig PV helps). Some might ask you, so just take the opportunity to inform them. That's one less person to support a vaping ban in your city or state. Carry some cards, like from CASAA that explains what an e-cig is. Avoid the use of the word cigarette. Call it a vaporizer and explain how you quit smoking with it. The word cigarette has bad connotations for non-smokers and that's who we need on our side. Never slip up and say you're "smoking an e-cigarette". That's the worse thing to say.
At restaurants, do it when there aren't people really close to you. In that case, it's usually best not to ask first. Most restaurants don't really care, unless they get a complaint. So they don't have any policy. It's a "don't ask, don't tell" situation. Bars are easier. I've never had a problem in a bar. Sometimes, I'll ask a bartender, but usually not. Most of them don't like smoking bans anyway. That's a good place to get used to answering questions. Plus, you can have a couple drinks first.
If someone gets hostile, or accuses you of smoking, just politely inform them that you're not smoking. Don't just immedately comply with some random stranger who can't tell vapor from smoke. Of course, it's different if they own the place or something. In that case, let them know you weren't smoking but you'll stop anyway. If you vape something that doesn't look like an analog, you can always tell people who are just being buttholes that it's a medical device. That shuts them up quick.
You'll get used to it. It starts in your own mind. You are not the one doing anything wrong. Don't blow your vapor in anyone's face and no one has any legitimate reason to complain. Few people will. Consider it your chance to possibly save someone's life. Don't be a sneak vaper. You're a non-smoker now. Spread the word.