What does this error message mean?

I am converting some tif files to 1200x1800 bit jpg files at 300 dpi  
and quality of 80.  On each conversion I got the following message:

convert: unknown field with tag 34665 (0x8769) ignored..

The tif files were 8 bit/channel with LZW compression.

The files seem to have been converted correctly.  However, their  
image in the Mac OS X browser is larger than images created by  
Photoshop Elements, and the little icon, instead of being a very tiny  
rendering of the image, is a default jpeg icon.

I can't think of anything else that might be germane.