Luckily, to experienced experts it all makes perfect sense.
Animals Asia's Vietnam Bear and Vet Team Director Annemarie Weegenaar, said:
Some bears do pull up the grass and bring it inside the den to build nests, but that wasn't the case here. This didn't surprise our observers, as nesting is more common in females. At this time of year with little rain, the grass gets a lot drier. We've noticed that a lot of the bears enjoy pulling and rolling in the grass at this time – probably because it gives a more tactile sensation than other seasons.