I'm so curious to hear how Riley is doing... my little man Bernie is having the same problem starting a week ago. Well, let me back up. When he was a baby (around 5-6 months) he'd have an accident every now and then while asleep. It happened rarely and I just figured it was because he's still a baby and was probably exhausted from playing in the heat (it was during summer) and just didn't realize. It only happened three or four times that I could remember.
Now while I was away for a funeral last tuesday, my mom was watching Bernie and said she woke up to him licking himself like crazy in the middle of the night. She went over to him since thats not normal behavior for him and noticed him and his bed was all wet! It's almost like he was embarrassed that he peed, and was trying to clean it up before anyone noticed! Two nights later, the same thing happened. I finally came home and watched his drinking and peeing during the day, which seemed normal. He's had three more accidents since I got back, the last being last night while he was laying asleep next to me on the couch!
Today he went to his vet and had the whole round of tests done. The invoice says they did xrays, cbc, serum chemistry, thyroid profile T4 and a urinalysis. I'm supposed to hear back from the vet tomorrow when I drop off the urine sample. Like you, more than the hassle of cleaning up and doing laundry every night, I feel badly for Bernie and just hope to get this little issue fixed and if not fixed, want to make sure it is nothing incredibly serious.
Sorry for the long post. Just venting and am in a way glad to hear that I'm not alone.