This doesn't look like Ich to me. In my experiences, ich generally seems to manifest in several places on the fish's body as small white granules rather than a single place in a larger white patch.
What's the mark then?
This looks like a missing scale or damaged scale which was probably caused by the wooden decoration log you talked about in your question. I have had frequent incidents where a fish (especially in a community) has been spooked by something and has caught themselves on drift wood or a decoration. They normally lose a scale but as long as your water quality is good, it should heal up no problem. Indeed, the only way to keep a fish in a pretty pristine condition is to keep them in bare aquariums with nothing in.
What to do next?
With anything like this, you'll want to test your water quality just to check everything is okay. If there is any ammonia or high levels of nitrate then @motosubatsu could be right. Ich is normally caused by poor water quality.
After testing your water and finding 0 ammonia, 0 nitrite and lowish nitrate, I would observe the fish for a few days. If this mark doesn't change or starts to fade, chances are it was just an injury from hitting a decoration and nothing to worry about.