-I was just building a nice looking house in creative mode, customized world, absolutely no mods or continuously running command blocks. I was placing carpet and a glass pane came out. It only seemed to work with the logs. I am not sure if this is only white carpet, or only oak logs. -
===EDIT===
Hey! I was using a shovel to make some path blocks, when suddenly I accidentally right clicked on one of the path blocks I had already created. This caused a glass pane to be placed. I did some testing. Anytime a non-solid block is right clicked with an item block, a glass pane will be placed. A normal, non-glitchy glass pane. There are also some weird non-intuitive block bugs unrelated to glass panes that I found. This looks like a HUGE bug.