Yes, I've heard this, I've always heard that facing South, or East are preferrable, I think that's because of them getting the morning Sun. I think the one thing most people try to avoid is facing them North because of the wind and winter issues.
I started with mine facing South, added a few more hives and put those facing East, and had a couple more late addtions that I ended up facing North...I'll probably try to reshuffle everything come spring, in the mean time I've just put a wind block in front of the two Northern facing hives.
Hope you and your bees are doing well! :)
Along the lines of what Coates is saying...I'm not convinced it really is that big of an issue, but I do think avoiding facing them North probably has some merit. If I rearrange, I'll probably end up with half facing East and half west, just because I think that will be the best layout for where I have my bees.