JCL here is what has happended with me. Two times in the last three weeks, it has leaked oil then stopped. Both times were consistent with the very cold temps (around 0 farenheit) outside maybe around 40 degrees inside the garage. There was snow on the ground so I did not have the X5 out for a couple of days prior to these cold starts. It was in the garage. It leaked upon start up then after things warmed up and was restarted the leaking stopped. Both times it was leaking from around the top of the oil filter cannister, then stopped. It has never leaked from there before. And I last changed the filter and large rubber O-ring about 6,000 miles ago. I always changed filter when I change oil. I checked to make sure the lid was tight and not over tight. I always hand tighten it then with water pump pliers tighten it another quarter to half turn. I just changed the oil and filter a couple of days ago and after initial start up there was no leaking that I could find. The two times it leaked before it left a visible pool of oil right below the oil filter.

My theory is that there is too much pressure in the oil delivery system maybe caused by some gunk in the OS and as you mentioned blows oil out the weakest link. If it is causing it to blow it out the oil filter, to me that is better than blowing out a valve cover gasket. Is this rational thinking?