Toxicity? Deficiency?

Hello RIU, I could use a little help here. When lights came on I noticed a bit of leaf damage.







Being a new grower I don't really know what the problem is. I didn't notice any of this before lights out. So I'm thinking this happened in the course of 6 hours. But I suppose it could have been there before and I just didnt notice but I don't think so. So any ideas what this might be or how to fix it? I don't see any damage on new growth





Any help would be greatly appreciated. Thanks.

Again. Any help would be appreciated.

Nothing to be concerned about at all. It’s just leaf minor leaf damage from physical contact or a small fluctuation in pH (usually during a dry period before watering)