We introduced the lab.js question only a few months ago. And it's not unlikely that users will find bugs, so we'll have to edit the question.
At the moment, there are no known and unfixed bugs in that question type. However, watch out for anything that does not work as expected, and also make sure to check the collected data.
You can also send us an information about your survey administration period via email. Should we have to change the question in that time, we shall let you know. However, I do not expect major changes at the moment.