Upper Pec Super Tight!

I noticed today that R/H upper pec and shoulder is much tighter than usual.  My last chest workout  on the 6th was not accompanied by any back work.  Push and pull exercises are some thing that I am trying to incorporate into my routine for natural balance and this tightness seems to highlight that train of thought.  It also draws attention to an inherent pec problem as this should not be the case just because I worked one without the other…?