Why is my beer sour

I brewed a porter for the first time. It spent a week in primary and a week in secondary, at about 70 F.

It has been in the bottle for about 4 days now. Not a long time, I know, but it tastes sour. Is this just because it hasn't been in the bottle for long enough?

The only other thing I can consider is that I accidentally splashed it a lot when I was transferring it to the bottling bucket. I'm sure that some oxygen got in there. Can that cause a sour flavor?

Which do you think is the most likely cause for the sour flavor...and do you think it will go away with time?

Oxygen will cause a cardboard flavor. It could just be green or it could be infected. I'm going with green. Leave it alone and give it time to develop.

It's way too soon to say anything about it......give it another 3 weeks