Two weeks ago I had a brew day in which we completed two all grain brews; A pale ale and a stout. I gathered grain and hops from various sources and drove off to my not-so-local HBS with assurances that they had a great yeast selection only to discover after over an hour of driving that they only had one vial of the yeast I wanted to use (white labs 007 English ale yeast). I got home and thought quick; I made about a half gallon of wort with a little malt I felt I could spare for the cause, then pitched my yeast into the starter wort around noon the day before brewing. Brew day came; I shook up the now bubbling starter and poured half of it in my pale ale and half of it in my stout. The beer fermented in my basement closet, which stays at about 65 or 70 degrees. Now it is two weeks later and the stout went into bottles the other day and the pale ale got transferred to a secondary for a dry hop treatment. Heres my issue: I tasted the stout and it tasted tart, almost sour. The roasty flavors covered up most of it but it was still there. The pale ale had the same flavor compounds, but with the absence of roasted barley it tasted tart, kind of like cider. It was my first time using the 007 yeast, and my fist time brewing batches this strong (both weighed in at about 1.070 OG). Have I had my first real infection problem? Has some wild yeast managed its way into my starter, or this normal for this strain of yeast? Is the cidery flavor normally associated with the slightly higher OG? Will this age out or get worse?