@Rashmi : I had almost the same situation few months ago. Not a coworker, but a family friend. I came out to one of my cousins, she was like, "OMG! You are the second person I know. You know Miss. XYZ right? She is a lesbian!".
I was so excited to hear that, I have a family friend who is gay, someone who my family and relatives know quite well. My cousin also told me that she is struggling to explain her family and there has been a lot of confusion in her family, after she came out to them.
I thought if we both connect, we can be support each other, show our families that they are not alone.. etc etc.. I added her as a friend on FB and said Hello. She responded a few times, until I told her that I am gay and have a partner! She immediately "un" friended me and stopped responding to me! I was shocked and very disappointed.
I thought about it a lot ...
* May be she is upset that she was outed without her consent. I would be upset too!
* I am very much out in FB and other places, which could have made her uncomfortable.
She probably felt that getting closer with me, would mean outing herself more?
* This is the worst possibility : She is very butch, which I think is super cute! She doesn't know how exactly I came to know about her. May be she thought, I doubted she is a lesbian because of her looks?
If she is not comfortable yet with the way she is, this could have pissed her off.
The sad part is I didn't even ask her about her sexuality, I just outed myself. Oh well!