pt-table-checksum shows diffs, but pmp-check-pt-table-checksum says "OK"

I’m new to Percona toolkit an Nagios plugins. When I execute pt-table-checksum, I see some diffs at some tables, e.g.

TS ERRORS DIFFS ROWS CHUNKS SKIPPED TIME TABLE
07-09T16:10:10 0 1 87 1 0 0.054 LDS.DATABASECHANGELOG

and the exit code is 16, telling me, that there are differences. But in the table check_sums I see the following line:

| db | tbl | chunk | chunk_time | chunk_index | lower_boundary | upper_boundary | this_crc | this_cnt | master_crc | master_cnt | ts |
| LDS | DATABASECHANGELOG | 1 | 0.011309 | NULL | NULL | NULL | 4090c657 | 87 | 4090c657 | 87 | 2015-07-09 16:10:10 |

showing me no differences. And pmp-check-pt-table-checksum shows

OK pt-table-checksum found no out-of-sync tables

What is wrong here? Do we have differences or not?

Thanks in advance!

Regards
Burkhard

same problem here ;-(