Puff of air from power adjuster

Hi all
I just noticed the other day that there seems to be a puff of air coming from around the power adjuster wheel on firing.
This doesn't seem to affect the consistency as I've chronoed it and shot to shot it's less than 10ft/sec variation.
Just wondering if this is normal or if I need to replace some o rings.
Cheers
Gaz
I just noticed the other day that there seems to be a puff of air coming from around the power adjuster wheel on firing.
This doesn't seem to affect the consistency as I've chronoed it and shot to shot it's less than 10ft/sec variation.
Just wondering if this is normal or if I need to replace some o rings.
Cheers
Gaz