Traversing a etherportal and getting attacked

I was using an ether portal to enter the ether and was attacked by  magma cube on the way through. I was sent to a new location in the nether. 

What I expected to happen was...:

i expected to complete my transfer and have to fight the magmacube at coordinates 552.78.348

What actually happened was...:

i was sent to 5800. 20. 5500.  When i step back thru the portal it sent me to 44000.40.44000 (numbers are not exact but within a fewblocks)

to return i had to die, and was broght back to my current spawn.  I thought the portal might have been damaged, but both original portals were fine.

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here...   i wish i knew
2. ...
3. ...

 

i am not sure if  this was a bug, a fluke, or expected.   But i wanted to let you know.

 

thank you