Oxidizing beer

[shish]

Transferred some Muntons Export Pilsner from my fermenter to a corny last night.

As there's several litres left over in the fermenter i poored myself a good 1/3 of a pint after i was finished and it was like :stun really nice, anyway i left a few mouthfulls in the glass, when i came back and finished it about an hour later it tasted . i take it this is the beer oxidizing... or i guess just plain going 'off'??

how much is this a problem when transferring from fermenter to keg?

I'm usually pretty careful about transferring it but as i noticed the kegged beer does have a little of the same backtaste i had in that mouthfull do i need to be more ultra ultra anal about not mixing air into it? - or is there something else going on?

[shish]

i have a better pipe setup now for doing it next time, we'll see after the next batch

...i'm driving to Belgium and Germany in a few days, return next Wed, we'll see what it's like when i get back.

oh and yes, i'll be sampling some of the local beers :beer