More traffic in qACK than non ack queues?

[mxx]

Sorry if that's a dumb question, maybe I should have posted this into qos forum, but since this is about 2.0 I thought it better belongs here since the shaper is so different.

Sometimes I see traffic in qACK of an interface being MUCH higher than the only other queue which is occupied at that moment.
I.e. All queues of a specific interface are empty, but qDefault and qACK. qDefault's traffic is about 25kb/s and qACK's is 100kb/s.

My question is whether I have configured something completely wrong.

The corresponding rule is under floating tab: quick, no interface selected, direction out, tcp, destination port xxxx, queue: qACK/qDefault.

Thanks for reading and for any help!

Max