Jon has a great point. I was initially going to say "no, it shouldn't taste sour", but if there is still yeast in suspension, yes, yeast itself has a certain sourness to it. Might taste just fine after fermentation is complete. Give it some more time and you'll most likely be awarded. Have you noticed any unusual looking pellicle on the top? If it was infected it would often have an ugly dusty looking skin on top that does not look like regular yeast. If it's the usual creamy brown with bubbles, then it's probably just fine. Patience.