Hello ToGo. A short length of hose on the spigot to reach the bottm of the bottle while filling with help eliminate oxygen in new beer. Oxygen at the bottling stage is bad, and will effect an after taste. The yeast is still at work when you prime;the oxygen during carbonation could give any number of undesirable flavors. Extract twang you can fix with boiling time, adjust for a late addition of a portion of the extract you use. Dry extract is normally fresher and stores longer; in kits it most often LME. Aging takes as long as you want it to, but the temp. where you store the brew will also effects the end product. If you did allow oxygen in during bottling and aged at the higher temps you mentioned then YES you will get off flavor. You have gotten alot of real good advice from various people on this problem. I would take all the answers, make a plan to follow step by step for your next brew and hope/know you did it all right. Clean, sanatize , good water , boil, clean bottle without any bubble, and store it a cool dark location(68 Deg.) . Chill em down in the fridge and see how they taste. There are alot of steps , but not just one answer. Make your plan and good luck.