Would a pot smoker ask?
Hells no.
Just flame up and blow the smoke at the other person like you are entitled.
I live in a state where pot is legal, and I can tell you, the smokers I've been around have courtesy. Once they ask if it's ok, they'll usually offer to share, they are a generous group...
Big thing for me, is the courtesy aspect. Which is missing in general from the public in my opinion. I love my freedom, hate when it restricts, and try to show everyone the respect that I expect in return. Some of the most judged sub-cultures, fandoms, and groups are some of the friendliest non-judgemental people you'll meet...and the most courteous.