The strange case of the bouncy bombs

[Conte Zero]

I took a HE111 for a ride on the country, with a heavy payload since I wanted to see the explosion nice effects everybody is talking about

So I was flying low over the fields and I dropped my bombs, working on F2 key and freeview to have a good angle to see my plane and the explosions on the ground

Surprise: after a short fall, the bombs hit the ground and started bouncing around like balloons. After a few second, they actually exploded, quite far from the point they were supposed to hit

I never had any problem with the patches, I only enjoyed the benefits, but this time I have this annoying problem (same with other planes, like Stuka, etc)

Anybody else?

PS - by the way, the explosions are actually very well done.