If you're not having any issue, flying at large events (think LARGE like Nall or IRCHA not a 25 person club fun fly) and are using adequate power to your receiver you won't have any problem.
I would suggest you check that you have the latest firmware on them by linking up the system and turning off and on the receiver. One of three things will happen.
1. Oldest - the system will link in about 3 seconds and the lights will come on steady (I personally wouldn't fly these)
2. Better - the system will link instantly and the lights will come on steady.
3. Latest - the system will link instantly and the receiver lights will flash indicating a brown out.