Just a few minutes ago, I found myself wondering if Fab (the booming online retailer) pulled a fast one to engender substantial goodwill.

Here’s the story:

About a month ago, I ordered a shower curtain with a roadmap of Texas (#onlyonfab) and an iPhone 4 case with a subway map of NYC (for my homesick New Yorker girlfriend) from Fab.

On Monday, I received the order, but with a subway shower curtain in place of the iPhone case. I immediately took a picture of both curtains and the invoice (which correctly listed the iPhone case) intending to send it to Fab to alert them to the mix up (and get my iPhone case).

Today, before I’d gotten around to sending the picture in, I got a preemptive e-mail from Fab identifying the problem, confirming that the iPhone case was in the mail, and ‘offering’ me to keep the subway curtain (how generous).

I was immediately impressed, it’s the first time in my long history of online shopping that a seller identified a mistake in an order within 48 hours of delivery. It’s amazing, really, and speaks to the quality operation Fab runs… or does it?

My shower curtain was probably not an isolated incident. It is highly unlikely that they’d catch a single mistake among hundreds (or thousands) and, as such, the goodwill this instance earned from me could be multiplied by the same number of orders.

What’s that goodwill worth? Noting Fab’s willingness to offer $25 credits for referring paying customers, it’s clear that they are willing to sacrifice some short-term gains for long-term growth and stickiness. A few hundred (or even thousand) shower curtains (or the like) wouldn’t be out of line with what Fab has spent on goodwill in the past.

I’m not trying to fly the conspiracy balloon here, I can’t say I’m even sure this is what’s going on here. It’s, at least, a compelling and clever technique for building consumer goodwill.

What do you think?