Anyway, I ran into her at a concert for a pretty big band she is a fan of. I work with said band. We talked a while and I got her back stage. If she truly thought I'm a strange stalker, she wouldn't have accepted my invitation.
I forgot to address this part. Almost everyone would accept your invitation to go backstage. Extremely rare is the individual whose integrity is bigger than spending a small quantity of time with someone you would rather avoid to get something that individual cannot otherwise obtain for himself or herself, like backstage passes to meet his or her favorite band. If Donald Trump painted himself in poop and asked me to follow him into Cassandra Wilson's backstage area I'd go as long as he didn't touch me. I'd even send a thank you note the next day because that's just good manners. What's more telling is that she never got back to you BEFORE the concert when she didn't know what strings you could pull. If Donald Trump left me a voicemail about Cassandra Wilson tickets, I wouldn't respond because I would have deleted the message the second I heard his voice.
Now the true test. You made successful contact ( probably by positioning yourself someplace she had to pass). Fine. Good! You created an opportunity by offering her something she wanted. Did she contact you yet to thank you or ask to see you again? Did you dispell any belief she might have that you are just a sad sack who likes to look but cannot step up by finally asking her for a date, pr even just calling her to stay in touch? Hmm?
Somehow, I'm doubtful. Your pattern so far is to run into her, and then let every newly opened window close. And then ask us how to reconnect after too much time has passed to not be awkward, and then disregard any suggestion to just push through the discomfort. Because that's your real problem. What you really want to know is if there is a way to talk to her that guarantees she will get on board with your agenda; there is not.