possible mold??

it depends on the rest of your growing conditions. if you control temp and humidity, you can almost grow plants right on top of each other. Another key is good air circulation.

 

First, it doesn't sound like you can keep your plants further away from each other.

But if you wondering about pruning to keep them from touching, definitely not. There is no more risk of mold from leaves from different plants touching than there is from leaves of the same plant touching each other. If you have a fan on them to keep 'em dancing then moisture can't get trapped between leaves. If the plants grow onto each other too much your may need to look at light penetration before mold as an issue, but for now just grow on.