Huge acetaldehyde in stout

[Benighted]

Hey guys I brewed an all-grain chocolate oatmeal stout a couple months back and after waiting around 4 weeks in primary I bottled it. I took a little taste of the beer and I noticed a huge green apple flavor. The beer has been in a bottle for around 2 months now so I decided to open one up. It gushed pretty hard and still had that acetaldehyde. Do you guys think this was because of an infection?

 

[day_trippr]

Concise article on acetaldehyde in beer production. Might give you an idea on what's going on...

Cheers!