Aamir

Hey guys,
I run KLM in R6, based out of Amsterdam Schipol, and with Schipol, gate availability is a major problem. After I hit the limits of my first five gates, I couldn't expand for a couple of days due to lack of gate availability.
When gates became available after a while, I decided to lease a gate to use, and lease three to keep for future expansion, as I had 3 777-200ERs coming in the next month and I didn't want them sitting around idle. I logged off then, and went to bed.
When I woke up in the morning, my 3 security gates were gone, even though I paid almost 1.5 mil for the three, and for a startup with only 15 mil (after AC leases), this is a frustrating loss. My 777s also had to sit idle for half a month until I managed to lease a new gate.
So my question is, if you have a gate and you aren't using it, and the airport has no gates available, will your gates go back onto the market after some time? If not, is this a bug?
Thanks