Yeh thats basically all it is..undigested food, coulda came out either end but more likely the bottom one.
If your beardie doesnt get his body temp up to the right level [high enough] or for long enough he may be unable to properly digest his foods...and its not like it can wait 4 hours then start to digest when warm is availably, itll move down and not be digested which is why its best not to handle atall straight after feeding [unless we are talking a couple mins, but even then a beardie can get distracted and forget he was going to bask]
And also the Hour each way rule applies for obvious and similar reasons, if too cold when eat still may not warm up in time to digest, or even may not have energy to safely swallow, and no less than an hour before lights go off cos sgain, the time needed to digest.
Might sound liek a hastle but isnt really atall, and im sure it didnt warrant a 3 page explanation ,sorry/
Anyway nothing to worry about if it happens occasionally, nothin atall, just realsie what it was caused by and dont do it again.
Oh...THE OTHER POSSIBILITY is that the basking spot temp is to olow, same effect ,different means.
The lower the temps, longer it takes to get up to temp and more often beardie must return...
Dean