Hmmm... yeah, I thought it was mostly about removing himself from the grief.
Look, a Wolfriders' noses is very sharp. I remember very well that after I lost my dog, seeing anything connected to her made my heart ache. Now, imagine that the one you have lost has scent trails all over where you live. Shushen's scent was still lingering in the Village, even after the ash. The guilt lay heavy, and so wrapstuff must have seemed appropriate at the time.
Next time, Dart awoke to recognition, thousands of years later. Considering that he had slept, the processing of the grief had not smoothed. Which means that Bowki must have had to deal with one depressed father. The little one might not have recognized just what it was, but known that something is off.
A wish to see his parents once more, knowing that they too were sleeping, and some grief which still clung to his skin must have convinced him to let himself be wrapped up again. By that time, his lifemates and child are long gone.