Am I Imagining the Tap?

No I feel that occasionally as well. Series 0, have had since launch.

 

I think all of us have had this same happen every once in a while.

 

If you are then my symptoms must be worse. I swear I can feel the odd tap on my wrist and I am currently wearing a Casio G-Shock watch.

 

https://en.wikipedia.org/wiki/Phantom_vibration_syndrome

 

I don't have an Apple Watch but I can't imagine it's uncommon; people get Phantom Vibration Syndrome all the time with their phones, so it's likely a similar thing with the Watch.

EDIT: @Julien just beat me to the punch!

 

I had a couple with my mechanical watches, too. Owners of 7750-based chronographs talk about the "wobble" of its unidirectional winding rotor, so I've wondered if I'd reflexively check my wrist for notifications if I owned a 7750 watch.

When I wear my Watch looser, especially when driving, it'll bounce on my wrist and I'll either think it's a notification or I'll ignore it -- and it could've been an actual notification.

Really not much of a problem, though. It's easy to snug down the band one notch for more reliable navigation taps.

 

i have the same issue. it's worse if you have the milanese bracelet. it occasionally does funny things on the wrist that replicate a small tap by itself.

 

Strange. That's the one Apple band I don't own. But I imagine that would happen through the band itself.

 

I have this experience with my Moto 360 as well.

 

God, happens ALL THE TIME with my Apple Watch Link Bracelet, and then I just look like a fool that keeps trying to make his watch relevant (trying to get others to notice it)

Have thought it was my arm like pulsing and getting blood through, because that's the best excuse I could come up with, however the logic part of me says that makes no sense

Worst part, once I check it, I put it down, and it happens again and I pick it back up right after, because this time it might actually be something (nope!)

Doesn't happen with my phone btw

 

Withdrawal symptoms from not wearing an Apple Watch?

 

Also, even when I'm not wearing my Apple Watch I feel it, go to raise my wrist expecting a useless notification

Nope, lol, not even wearing it

 

Sometimes I can hear a notification on the iPhone but once I check I see no messages or other notifications, so it has to be a bug.
It happens on the Watch as well, but I feel the vibration instead of hearing a sound.
I read about the syndrome, but since I can hear a notification sound I doubt it is my immagination

 

You need to go back and reread it then.

https://en.wikipedia.org/wiki/Phantom_vibration_syndrome

"...Phantom ringing may be experienced while taking a shower, watching television, or using a noisy device. Humans are particularly sensitive to auditory tones between 1,000 and 6,000 hertz, and basic mobile phone ringers often fall within this range...

 

In the past I thought I experienced the syndrome because I felt vibrating on the back were I put the phone, but I didn't receive any call or text message (I'm talking about the pre smartphone era).
What I didn't mention in the post you quoted is that me, and other people, hear the notification. I guess it is hard for two people in a room to experience the syndrome at the same time.
Last time I was in my bedroom, the tv off, and my wife told me "you just receive a text, I think is your phone" but none of our iPhones had any notification and we both hear the sound. I'm pretty sure it came from my phone because is closer to me.
Maybe it was the sound of an old notification delivered after some minutes.

The Watch receives notifications only when is on my wrist so during the night I can't feel anything. I'm not sure it is a bug, maybe I'm really experiencing the syndrome with the Watch during the day. My point is that there is a bug in iOS when dealing with notifications, so a similar bug may exist on watchOS