MerCruiser Tune Up

Question
Recently, I had a tune-up and oil change performed on my 1994 SeaRay 330 Sundancer.  The two engines, MerCruiser T-5.7 Liter, 260 h.p., had 400 hours on them, had received several oil changes in the past, but not a tune-up.  Original spark plugs had never been changed.
During the first trip out after the service work, the two throttle levers were no longer in sync.  In order to maintain both engines at an equivalent RPM level, the port throttle lever had to be positioned about one inch more "open" than the starboard throttle lever.  
Is this a problem, and if so what causes this situation?  To me, it appears that the port engine is requiring more fuel to run at a similar RPM to the starboard engine?
And, will this situation correct itself after the tuned-up engine becomes more "broken-in" after the new plugs, filters, etc... become conditioned?
THANK YOU VERY MUCH!

Answer
Hi Jeff, It maybe happened during the tune up prosess that the port throttle cable MAY(?) have been removed for one reason or the other and not returned to the same setting this is no big deal,just a simple cable adjustment will cure the problem----Have fun,be safe,God bless!!