Bulbs hard resetting at different rates?

I have three bulbs that refuse to be added to my network even though they show up as “New Bulbs” in the LIFX app and I’ve been able to add 7 others recently that function correctly. All bulbs have been updated to firmware 1.20.

What I’m wondering about is a strange behavior that I’ve noticed with these particular 3 bulbs. When I do a hard reset by flicking the light switch 5 times (all three bulbs are in one light fixture), at least one of them cycles through the primary colors at a different rate than the others. Is this a hardware failure, a question of different electronic components in the bulb (older chips or some such thing), or related to the firmware not installing correctly?