First AG - Slight sour taste

[giraffe]

I am drinking my first attempt at an AG pale ale and it has a slight sour taste to it. It has been conditioning for about 4 weeks but the taste is still there. Any ideas of what it could be? I don't think it's an infection as it isn't that strong, it's almost like it is lacking any sweetness, like a dry wine.

It was a simple pale ale, just Marris otter and cascade, US 05 yeast fermented @20c.

 

[BrewsWayne]

https://www.bjcp.org/faults.php

 

[Duxuk]

A lack of sweetness could come from too low a mash temperature in an AG. The higher you mash, the more unfermentable sugars are left to sweeten your finished beer. You can also consider grains like crushed crystal to add flavour and sweetness.
Late hops, especially, leave a slight acidity which with a dry brew might seem like a sourness.
Hopefully it's still drinkable

 

[foxbat]

An excess of sulphates in your water can cause that very dry flavour. A bit like the original Burton ales.