Contacted a great traveling provider the other day to see if I could book a morning appointment on the day she was leaving town in several weeks. I've seen her several times before. She told me she was only booking 90 minute sessions to reduce clientele because of covid risk. I had requested an hour appt. I jokingly replied that to reduce my risk I was masking up, doing more half hour sessions and doing doggie style. She accused me of wasting a lot of her time and demanded that I send her a gift. I apologized several times but she kept demanding a gift. It was strange! Was I out of line for discussing a topic she had brought up.

No way in hell were you out of line  
You requested a date matching length of time from the past( think is true)
She  responded and you responded  
She just wasted more of her time asking / demanding a gift

Not for asking for an hour long session, but for the fact that you "apologized several times" for it.

I ran this by my fellow scriptwriters and it was unanimous: too much drama. In the rewrite, she counters your joking reply with her own, "Well, to be really safe, venmo me $300 and we can do an hour by skype." You then chuckle and say, "Nah. I'll just wait for your next trip here. Take care." "You too!" "Have a Happy New Year!" "Yeah! You too!" "OK. Have a good, safe trip. Bon voyage." "Thanks! Love you." "What?" "Nothin'. See you next year. Bye." (click)

Sounds very bizarre indeed to me, especially with a previously known and possibly recent Client who would not even require screening.  
I have found that with the events of the last year that I have often found it necessary to stop and take pause  and reflect for a moment to consider the pressures that everyone is experiencing.  Not normally an extremely patient person especially with rudeness and a lack of gracious behavior i try to be understanding and make comparisons with what i have/am feeling but it can be difficult.  Learning to bite my lip is leaving  (figuratively speaking) some bruising, I am normally outspoken and BRUTALLY frank.  It has been a struggle for me and I know others too.
I don't know where she AT or WHAT she may be experiencing but it sounds like another case of the COVID Panic Behavioural Syndrome  ( otherwise normal people doing totally bizarre unexpected things for no really good reason)  to me, ......but really, who knows what the Hell she is thinking or experiencing.

A rather excessive response to what seems to have been intended as a humorous reply. However, probably worth keeping in mind that what we hear in our own head, and even how something might come across verbally, are often different when read by someone else.

but I don’t see that warranting you having to send her a gift to make up for it.  

I have to see you next time you're in Mpls.

"You have wronged me; pay me money." What a money-grubbing . . .

with providers I know well,  so my take is that if this is a lady you see once a month or more often, then she should have engaged in the playful banter you started to try to work out some sort of compromise.  She drew a line in the sand and left herself no way to walk it back.  That's on her.  On the other hand, if she's a provider I have only seen once or twice before, or have not seen for many months, then I would  refrain from too much kidding around during the booking phase.  I would have soberly explained to her that all I can work into my schedule at this time is a one-hour session, and if she is not able to do that, then I would still be interested in seeing her in the future if her policy changed.  That's all I would say, and then wait for a few days for her to change her mind and take the one-hour booking.    

You could just tell her to fuck off and find a less demanding, less "cunty" provider.  

Now I think she may have blacklisted me. How can I find out if im blacklisted?

I think she may have blacklisted me. How can I find out?

"great" she really is, and the regards in which she holds you as a repeat client.  

Better just buy her an engagement ring and get it over with because you act like you’re married.