INFOPATH: SOAP error on publishing list form

Noticed an interesting behavior: Publishing an updated Infopath form (only change was to make one field mandatory) created a SOAP error (msg: cannot publish form, item may have been deleted). I had an event receiver for the list that would respond to itemAdding() and itemDeleting(). When I disabled the eventreceiver the form publishing would go through fine.

What puzzles me is that the eventreceiver that works on list item events would have any interaction/influence when a list form is published. A list form is not a list item, is it?

Thanks for any enlightenment...