I'm not sure if there is an "official" change in BCG hold time or not. I have see posts on Dr. Lamm's website stating that a 30 minute hold time may be adequate to receive the benefits of BCG therapy. Personally, I try for 2 hours hold time. If I can't hold it then I just go to the bathroom and don't sweat it. The fact that I've seen a shorter hold time suggested on Dr. Lamm's website makes me not be concerned if I don't get the full 2 hour hold time.
askdrlamm.bcgoncology.com/category/bcg-general/page/9/
There is one link where he advocates a shorter hold time. I know I've see it in a few other questions he's answered on his website as well. Dr. Lamm is considered an expert on BCG treatment and basically developed the protocol we use today. If it's good enough for him it's good enough for me.