If it looked like this, it's normal. I always take a ton of pics of my gliders to see things in finer detail, the other day I got a glimpse of the red and went back to review the pic, it's normal and retracts once to poo has come out. You don't always see the red so when you do its like wth is that !
However, if it wasn't like the pic n was liquid or blood/bloody urine she'll need a vet appoint. Weve had a few cases lately of Pyometra. One of the gliders had a bloody discharge one time so it's on our list of symptoms for pyometra.