Leaves curling

Whats up.My plants have been doing really good.Today around noon the light was turned on and I noticed there were mites.I got the spray for the mites.But now the biggest plant about 2 months old had its leaves start curling is this normal or something I should worry about.

You will have to upload some pics. The first thing you need to do is think about what you changed between your healthy plant and now, i.e nutes,water,light. Also what did you use to kill the mites? Please dont say Diesel fuel.