Green apple taste with beer that used bucket with lid with no gasket

I kegged a black porter, from an extract kit 4 days ago, it is still carbonating.

It has a green apple taste to it.

I let it sit in the primary for 7 weeks, a midwest supplies 6.5 gal bucket w/ a lid that does not have a gasket.

I transferred to a big mouth bubbler for 7 days and then kegged.

I recently brewed another beer, using the same bucket and lid and you can tell there is pressure in the bucket, as the lid is pushed up toward the middle of the lid, when I push down on the lid gently, bubbles come thru the airlock. The airlock is not very active, I think air is escaping since the lid is not air tight. I consulted an employee at midwest before buying the bucket and lid and they assured me it is fine and I have read on here about other people having similar concerns about lids w/o a gasket.

I have had other beers that had a green taste to it and after a couple weeks in the keg it mellows down.

I am looking for some insight as to what may of gone wrong, did I keep it in the primary too long? That is my first thought. I'll definitely only have it in the primary bucket for no more than 2 weeks going forward, as I use my big mouth bubbler for secondary.

Also, it brewed at a decent temperature and I sanitized all the equipment, reading up on green tasting beer leads me to believe it had to do with too air exposure.

I also used us-05 dry yeast and it took about 30 hours for the bucket lid to show that it had built up pressure in the bucket.