Verified fixed by OP.

Changes have been made in Git (master):

commit 2367fd9ab913b3a25fd358049e838c69e33d8c6f
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Thu May 30 17:20:14 2013 -0400

     Ignore the OPTIONS node for SMS until we support it.

     Client really shouldn't be sending this unless SMS is selected for sync,
     but this prevents corrupting the sync cache with the incorrect 
collection class
     if it does.

     Final (?) fix for Bug: 12281

  .../lib/Horde/ActiveSync/Request/Sync.php          |   31 ++++++++++++-------
  1 files changed, 19 insertions(+), 12 deletions(-)

http://git.horde.org/horde-git/-/commit/2367fd9ab913b3a25fd358049e838c69e33d8c6f

Changes have been made in Git (master):

commit 7493e8cef3be48a4c814c6a5f1ed1e16148c14ee
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Thu May 30 12:06:40 2013 -0400

     Collection Class might be sent in OPTIONS when EAS > 12.1.

     Fixes sync for clients that attempt SMS sync. Possible fix
     for Bug: 12281

  .../lib/Horde/ActiveSync/Request/Sync.php          |   11 +++++++++++
  1 files changed, 11 insertions(+), 0 deletions(-)

http://git.horde.org/horde-git/-/commit/7493e8cef3be48a4c814c6a5f1ed1e16148c14ee

Not sure what happened to my commits@ message, but this is most likely 
fixed by:

https://github.com/horde/horde/commit/7493e8cef3be48a4c814c6a5f1ed1e16148c14ee#framework/ActiveSync

Can the OP verify this is now fixed?

Sure. Not a problem.

Ok, I'll get it for you. This problem seems to only happen with my 
Samsung Galaxy S3 for some reason. It doesn't seem to matter that I've 
deleted the activesync entry for this phone via web interface, or that 
I've deleted the whole account from the phone as well. The problem 
doesn't exist when reading the same account via activesync using for 
example Nexus 7 tablet.

Can I mail the activesync log directly to you, as I'd not like to make 
it public ?

Cannot reproduce.

I would need at least the activesync log, not the IMAP log.