Building physical simulation (Bullet3d) for iPhone SDK 2.2 leads to different results than in SDK 3.0

Question

We are building a simple rigid body 3D collision application using Bullet3D on the iPhone. When testing it, everything goes fine on the simulator and on the iPhone SDK 3.0. When trying it on the iPhone SDK 2.2 some rigid bodies pass through each other... any idea why?

We assume it has to do with (the not verified) fact that Xcode uses gcc 4.0 when compiling for SDK 2.2 and gcc 4.2 otherwise... and this might involve some changes in the floating point precision.

Any idea why the same application should have different computational behaviours on the two SDKs? Any advice on Bullet3D?

Thanks,