So, I googled the ostensible quote from the Houston mayor, and not a single article mentions WHERE or WHEN or to WHOM this statement was made or the context, nor do ANY of them provide any attribution.
In fact, there are just a few hits on the quote and they pretty much seem to all be in a circular echo chamber of couple dozen 4th tier web sites.
It may be true, but at this point it looks apocryphal.
It shows up on her twitter account. Apparently she said it in passing to "Lone Star Q" LGBT blogger John Wright, during a telephone interview. He blogged about it but hasn't published the full text of the phone interview.
Her choice of words was wrong, offensive, and unfortunate. It sounds like she wasn't sure if she was going to brush the whole controversy aside, or use it to shore up her image in the gay community, or try to crush Robertson.
If Parker had been more measured and polite, though, she might be getting the same kind of responses, based not on her language but just on her (inevitably) taking the "gay" side in the controversy.