Blueberry bush in container

I have a dwarf blueberry bush growing in a container in my yard (planted within the last 2 months) and for a while it seemed to be doing very well but all of a sudden, the leaves have been turning red and falling off. Is this normal for this time of year? I live in the San Diego East County. I do not believe I am overwatering the plant since it is on a drip system and gets a little watering twice a day.

I have a couple of blueberry bushes I planted in a small raised bed, kind of similar to a container. One of the varieties does turn reddish and lose its leaves; the other does not. I live at the coast, so mine hasn't turned red yet, but I think it is pretty normal for that variety. I don't remember which one I have. It comes back just fine in the spring. Tanya

Blueberries like acid soil conditions to perform well. This usually means mixing in quite a bit of PEAT MOSS when you plant. Also fertilizing with and 'acid type' plant food. Perhaps a "Camellia Azalea Fertilizer".
You also need to double check your watering, you mentioned a dripper, you need to find out how much water it puts out. Most are calculated in 'gallons per hour'. If yours is a 1 gallon per hour emitter and you are watering for 15 minutes that is only one quart each time. This may not be enough. Of course, I don't know how long your system is on for each segment and I don't know the gallons per hour of the emitter. Just some things to check. Also like the other person said, some do turn more red than others, it depends on the variety. I think it is a little early for them to be changing color, however.