no mpls ip propagate-ttl forwarded

I tried "no mpls ip propagate-ttl forwarded" in MPLS lab but does not work
exactly as described in some tutorials, including the following Cisco
tutorial:
http://www.cisco.com/en/US/tech/tk436/tk428/technologies_tech_note09186a008020a42a.shtml#mpls_tracerte

When tracing from CE to CE I get a reply from latest MPLS router like in
example below:

R1--R2--R3--R4--R5

R1 and R5 are CEs (no mpls configured)
R2, R3, R4 are MPLS routers.
R2 and R4 are configured with command "no mpls ip propagate-ttl"

Trace from R1 to R5:
R1#trace 10.1.45.5
  1 10.1.12.2 8 msec 8 msec 4 msec
  2 10.1.34.4 12 msec 44 msec 20 msec
  3 10.1.45.5 24 msec 32 msec *

According to the Cisco tutorial I should only get two replies, from R2 and
R5. In my case I have also a reply from latest MPLS router (Line 2)
Why ?

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Received on Thu May 19 2011 - 13:24:24 ART