As mentioned, every throw of a die is independent, however, let's make this a bit more interesting!
Let's say that on your first roll you do not roll a 5. There is a 5/6 or 83.3% chance of this happening. You can see this by subtracting the chance of rolling a 5 from 1 like so:
1 - 1/6 = 5/6
There would further be a 69.4% chance of not rolling a five on the second roll:
(5/6)^2 = .694
Or another way of saying it is that there is a 30.6% (1 - .694) chance of rolling a 5 in the first two rolls of a die.
If you continue this pattern up to 38 rolls of a die then you reach:
1 - (5/6)^38 = .999
Meaning that if you roll a single die 38 times there is a 99.9% chance that you will roll a 5.
So if you roll a single die 38 times without rolling a 5, then surely there's no way the next roll won't be a 5!
There. Glad that's all cleared up then.