Every Wednesday, I work my chest, shoulders, and triceps. Here's what I do:

Flat Bench Press (3 x 8)
Pec Deck (3 x 8)
Arnold Press (3 x 8)
Close-Grip Bench Press (3 x 8)

I've just started back up on my routine after Winter Break. So, I've been doing this routine for a few weeks. During that time, the weight that I Bench Press and Pec Deck has gone up. But the weight that I Arnold Press and CG Bench stayed the same.

Though my Arnold Press and CG Bench exercises aren't going up in weight, does that mean that my shoulders and triceps aren't getting stronger? Or does it mean that the Bench Press tires me out so that I can't Arnold Press and CG Bench to my full potental? I feel like this might be the case. If so, do you think I'm overtraining my shoulders or perhaps even my triceps too? My shoulders and triceps usually aren't too sore (my chest is a LOT more sore), so does this mean that they can't be overtrained? Or can muscles that aren't sore still be overtrained?