We've received some reports of this. Right now, we are trying to track down the variables as it is affecting some and not others, which makes it more specific to the mobile environment (such as operating system and maybe type of phone).
In our own direct testing, we haven't been able to reproduce the problem. However, many of the reports seem to be from those using a model within the Samsung Galaxy line, but there have been a couple others mentioned.
This is a recently reported issue that we hope to have resolved ASAP. At the moment, we are gathering information such as phone model, operating system version number, and browser details and asking all publishers to clear their cache/history then check to see if the problem also occurs in our demo environment (which narrows things down considerably).
Any details you can provide from your client would be very helpful and much appreciated.