There has been a firmware update in Jan 2013, version 2201074_229181 dated 16 Jan 2013.
We've had the same problem on M4555 and M575 printers as well.
I have not heard of any problems with our lone M525 after this firmware update but cannot confirm it is corrected.
I spoke with HP support engineers in March 2013 explaining this issue specifically on our M4555 and was given a beta firmware version which helped but did not completely correct the issue. They told me at that time that they were working to release a new firmware "in the near future" that would fix this issue but I have not seen the firmware released yet.