Is it possible that this could fail even after only 6 months?

So far.
~car jumps from 1st to 2nd
~did the brake test engine lifts about an inch and a half
~no oil leaks or tears from mount
~vacuum line is attached

 

yes, it can.
Also if the rear one is broken as well, and you change only the front one, it won't last long. Ask me why I know that

 

Removed the rear an inspected it and no visible signs of failure and no oil leaking.

When I did the brake test it lifted from the front.

 

check your tranny mount too..

 

Yeah, check the other mounts....also closely inspect the top passenger side if it wasn't replaced when the front one was done.

 

A brake test showing lifting from the front means nothing. If the engine lifts more than normal, they are all toast. Do the job right the first time by replacing all of them.

 

half an inch seems normal to me. When they're shot it will rock back and forth 3+ inches and produce a good solid thump !

I'm confused and to what you mean by "jumping between 1st and 2nd". Do you mean thumping ?

smarty

 

Yeah, I agree with Smarty.....a better explanation of the car's "1>2" jumpin' may be helpful.
Have ya checked the tranny fluid and have ya had any other related issues ?

 

The jump is more of a thump. Definately can tell the car is going into 2nd gear intermittently.

~transmission is brand new (remanufactured from honda)
~no oil leaks from any mounts or damage.
~replaced front and side mounts 6 months ago

 

So ya removed the rear mount,...but did ya replace it ?
How about the two tranny mounts ? Have ya checked the suspension and sub-frame ?

Other than the mounts and basic underbody support, ya may need to investigate the tranny itself for internal issues.
Take it back to where the new tranny was installed.

 

Did not replace rear motor mount no defects were detected...
Transmission mounts are in good shape.
Everything you and others said check out, the new tranny has an 18 month warranty so that is an option.

What about axle?