It is VERY likely that increase in ping time was when your device was 'doing something' (like checking mail, updating software, doing a check out against the network for something, etc). Random blips in the ping latency are almost always that, and the only way to ensure it's not is to uninstall and disable all essential and non-essential software that would need network connectivity (which is kind of not doable). A far more effective measure of the quality of your connection is to do a speed test using iPerf, Ixia, etc, but again, the above is relevant as the device checking for mail will show a decrease in throughput.
It could also be your device going in and out of powersave mode, which on some devices you can disable by turning off power-save, or by setting the wireless card to 'aggressive' or whatever setting indicates it will use the most power.
If the majority of your pings are fine and you just see those blips, it's likely just fine.