Everyone with apnea never had it until they did.

IOW, while it's possible that gabapentin had something to do with your apnea (people respond differently to meds.) it could also have been coincidence, or that you already had apnea which was exacerbated by the gabapentin. Here's why I think so....

Googling: gabapentin side effects apnea turned up one site (I did not review all - just the first page) that listed apnea as a possible side effect, but several links to instances of gabapentin being prescribed by sleep apnea doctors (for a variety of reasons) including for sleep apnea.

Googling: gabapentin apnea turns up a very few cases of gabapentin exacerbating existing apnea, but in most of the links I reviewed (on the first page) including one here on NT:

http://neurotalk.psychcentral.com/thread66697.html

gabapentin had either no effect or actually improved apnea.

In one study of nearly 20,000 patients who take gabapentin, zero reported apnea as a side effect.

My wife & I both have apnea requiring cpap machines, and we've both been prescribed/taken gabapentin, but both our apneas manifested before the gabapentin was prescribed; it's extremely common as a part of (middle) aging.

Doc