If the plumbing is PVC, that's strange that it is loose. Do you think that someone forgot to glue it? If you're able to take it loose and determine that it isn't broken somehow, and it it will go back in cleanly, there's no reason you can't re-glue it.
Thanks for the comeback. I am now going down in the crawl space to fix it. I might be able to pull it back bout an inch or so to make a glue job. It's at a very awkward spot to work(no room) at the fitting. I really don't want to rip the entire junction area apart(big job).