For the record, I'm a loyal Adafruit customer but this question involves a part purchased from other "other guys."
I purchased a few of these 1.5" OLED screens:https://www.sparkfun.com/products/8537
They're great. I use them in a mod for a pinball machine, and they're powered by a 5V source on that machine. I also attach three LEDs in parallel to the 3.3V output on the OLED screen. The LEDs have glowed brightly for months but, over time, the LEDs appear to suddenly fail. This has happened on multiple kits I've made. They do not light anymore, as if they've experienced a surge of voltage, though the OLED screen is fine.
What can I include in the parallel LED circuit to protect them? Is there some kind of simple fuse that would stop voltage from going above 3.3V? I've read a little about Zener diodes but I don't know if that's what I need, or if some kind of real fuse would be better. I'd rather not have to replace components -- so a self-resetting or robust component would be ideal.
Thanks for any suggestions!