This is your ATF we are talking about, not some random civvie chick, why would you be surprised to see a provider at an "adult" establishment?

She could be there as part of an appointment, in which case discretion would be the rule of the day. Or she could be there for any number of other reasons, several of them which could have led to a much more enjoyable evening than the one I am wagering that you actually had.

So I was at a strip club and  one of my favorite pornstars was feature dancing and I was enjoying myself.

Near the end of her show I had to do a double-take when I saw my ATF taking a seat on the other side of the stage.

I felt awkward so I left after she was done dancing.

I'm wondering why you felt awkward.
A bit surprised maybe. Be discreet of course, but leave? I wouldn't have.

Buy her a drink!

Make eye contact, smile.

She was probably there to see one of her friends. She might have chatted or hugged you. Most likely she would have smiled and politely let you know she was "busy" atm. Nothing to lose especially if you were polite and discreet about it.

Who knows she might be friends with your favorite porn star.

My plane was early arriving home from a business trip when my work associate and I got the idea to stop by a local gentlemans club where a hometown porn star (she was a actually a "dance" graduate of a local and somewhat nationally prominent university) was the feature intertainment.

We got there just before her show and ordered a couple of tall, cool ones (beers that is).  Just a few minutes before she comes on, and just as are beers are arriving a dude come by and asks us to sign a "release".  Seems Inside Edition was filming a segment on the young lady that very evening.

We never touched the beers.

Needless to say last thing we needed was to show up on the evening news.  Damned shame but we were out of there before you could say Hyapatia Lee!

I said I wasn't interested.  I think it was for the part Taxicab Confessions where they show snippets between cab rides.

She was there with a guy and I know she doesn't go on outdates with clients. I was surprised to see her.  Since it was a very small place, odds are we'd run into each other I figured it best to leave since this was the first time I ever saw her in public and I don't know if he knows anything about what she does.   I know she gets uncomfortable with the idea of seeing a client outside the bedroom so I was taking her feelings into account as well.  For this reason it felt awkward to me.