Yeah, it was a brand new bag, and everything was potted at the end of April, and they've been outside under the shade cloth for about a month. And these are "orchid pots" with holes. I'm not overwatering (I don't think -- everthing is thriving) and I figured it was just the result of the lower light from the shade cloth, humidity, etc.
Although I have to say, I don't mind repotting. I find it really relaxing and therapeutic. So, if it's every 5-6 months, so be it. At least I won't wonder what to do with the HUGE bag of sphagnum -- the only size sold at the local nursery. Does it get old and bad if not used right away? I'm storing it in the plastic bag it came in, with a plastic grocery bag upside down over the top to keep stuff out, on a shelf in the garage. Should I be doing something different to store it?