An environmental monitoring station measures the gamma radiation emissions from a soil sample containing a long-lived isotope. A digital sensor records the number of counts detected in consecutive 5-minute windows and outputs the following dataset:
| Time interval / min | Detected counts |
|---|---|
| 0 to 5 | 112 |
| 5 to 10 | 94 |
| 10 to 15 | 127 |
| 15 to 20 | 103 |
| 20 to 25 | 118 |
A technician reviewing the log suspects the sensor is faulty because the recorded counts fluctuate significantly between intervals.
Explain why these fluctuations do not necessarily indicate a sensor malfunction, referencing the fundamental nature of radioactive decay.