I'm currently on a 4 day lifting plan.

Monday :: lower body
Wednesday :: chest and arms
Friday :: lower body
Sunday :: back and shoulders

If I cut back to a 2.5 day a week maintenance program over the summer that looks like this...

Days 1 & 2 :: Full body routine utilizing mostly compound movements

The Half day :: focusing specifically on chest and bi's and tri's

Will I end up with muscle imbalances at the end of the summer when I switch back to a 3 or 4 day a week split?