Cider fermented too tart

I've just bottled a brew but find it's fermented out very tart.
Recipe as below:

1 gal of store bought juice
1/2 cup of brewers sugar
2 1/4 cups of light spray malt
1 cup of brew enhancer (light spray malt and sugar blend)
1/4 tsp of nutrient
1/2 tsp pectinase

also very light hopping

og was 1.080

fg 1.006

I racked it about 3 weeks ago and at that point it was good still had some light malty tones rather easy drinking looking at my notes I said nothing about tartness or acid bite gravity at that point was 1.006.

at bottling the fg was 1.006 but the flavour has changed totally no more malty tones just a tart acid bite.

is it poss that in the 3 weeks from racking I have managed to have acetification start?

I was very careful with my racking so as not to splash.... topped off the 2ndary with more juice from the orig mix less than 1 inch of head space and it was kept under air lock.

when drinking the Cider has great body but the acid is felt down the sides of the tongue and in the back of the throat.

This seems to be happening to me a bit I know I'm not testing the ta or ph of my juice to begin with so this could be a problem, but I find it weird that at racking the taste is fine yet 3 weeks later with little signs of fermentation and no drop in gravity and I have a completely diff brew.

Have you tried/made cider before? It generally is rather tart and once it ages at least 6 months it mellows out. After a year it is even better. If it was infected it would form a thin white layer on top, mold or have a change in cloudiness.