I’m testing my module, and I’ve found that out of about 150 die rolls of a six sided die, one of my random text buttons only rolled a “5” once. My module requires you to prospect an asteroid by rolling a die twice - with a 6, followed by a 6 being the best result, but a 6, followed by a 5 would be excellent. That’s unlikely, but it’s never happened. This is created through the use of a random text button, that simultaneously rolls both dice. The strange thing is, that while rolling a “5” with the first button has happened four times, (probably fewer than should happen), with the second choice it has only happened (any number from 1 to 6 followed by a five) once. Should I be worried about this, or is it just that you have to roll dice at least 1000 times to get a proper spread of results?
150/6=25
So, on average, out of 150 rolls with a single D6, a “5” should come up approximately 25 times. This should be true for both rolls, since the way you describe it they are independent of one another and are not combined to get single result.
My answer would be, yes, you should be worried.
(Someone correct me if I’m wrong because I can’t count the number of times I failed math.) 
What you describe is unlikely, but could be a one-off random event. If you get the same results for the next 150 rolls, then I would like to see your module.