I had a field case and a bump case. The field case expanded on me, but the bump case remained tight as a glove in all the time I had it. If the executive case is made from the same harder material as the bump case, it will not expand on you.
I find it strange that the TPU can expand despite its rigidity. I believe the executive is made of the same material as the original field case, but bear the slightest hope that there is an improvement in this issue because i really like the form factor (the grey/black combi of bump case also doesn't appeal to me).
That said, does your bump case reveal the silver bezel around the iphone?