He may have caught in the act of finish grooming itself. They tend to salivate during the process and the red/brown bits were probably bits of the substrate. Just a guess on my part. I've seen mine do the same but has black bits. I use topsoil for substrate with sphagnum moss scattered by their hides.@Therasoid
it is quite large , while i was at work i got a txt of my son saying !!! your new T looks like its loosing from its mouth/fangs, but buy the time i have got in there is nothing there to see ???
P.S he said the fluid was mostly clear but it looked like some red/brown bits in it !!!