Not normal, but not unheard of.
At 5 months, she's still learning about the world around her. If this was a one-off, she may have (most likely) mistaken some movement or lighting or debris, etc. for prey. Or was just 'experimenting' (for lack of a better explanation),
If it continues, it could be something else like a nutritional deficiency.
But let's not jump the gun until we know a little more....

Anything changed about the enclosure or husbandry?