Warp point slip bug?

[Q]

SE V version 1.33; BM version 1.05:
I had several combat ships on a warp point and some unarmed enemy ships (mine sweepers) in front of that warp point. The next turn these enemy ships were in the system on the other side of the warp point without any combat occuring. I checked their design and they had no cloaking device. They seemed to have sliped by my combat ships on the warp point sector.
Anybody seen similar? Is this a bug??

[Q]

I found it:
The warp point has "unusual gravitic" activities that mask ships from basic sensors. This information is not very obvious however.