MCH0602 Boundary alignment error

I've a service program that was returning 5 chars long varying field.  I
changed it to return 25 chars long varying field.  See below
 
Was:
P VT100GetControlChar...                      
P                 B                   export  
D                 pi             5    varying 
D  piName                       25    value   
 
Change To:
P VT100GetControlChar...                      
P                 B                   export  
D                 pi             5    varying 
D  piName                       25    value   
 
 
I re-created the service program but did not recompile the caller
program.  Caller program is doing the following:
C                   eval      mySendThis =                              
C                               VT100GetControlChar('TB') +             
C                               '2' +                                   
C                               VT100GetControlChar('TB') +             
C                               'abcd' +                                
C                               VT100GetControlChar('TB') +             
C                               'ACCEPT' +
VT100GetControlChar('SENDEOT')
 
 
When I run the caller program, I'm gettting the MCH0602 error.  I was
under the impression that I do not need to recompile caller program as
long as the change that I made to the service program doesn't cause the
signature to change.  Is that a wrong assumption?