3.77.3.99 vs. 3.81 and defines

[PATTON, BILLY \(SBCSI\)]

In the current production release of all the makefiles there are many
define statements.  In the file where I found the problem they are like

<sp><sp><tab>define xxx
...
<sp><sp><tab>endef

But one had
<tab><tab>define yyy
...
<tab><tab>endef

The one above worked fine on 3.77 and 3.79,  but 3.81 crashes and says
that it cannot find a matching endef

When I changed the one statements to
<sp><sp><tab>define
...
<sp><sp<tab>endef

everything is ok

Now when management asks questions like :
1. why wasn't this a problem before?
2. Will it effect all the other systems still configured with 3.77 and
3.79.

We need to know that it will not effect all production by making this
change.
To my knowledge it should not effect anything, especially we will be
changing a unique instance to make it like all others.
Do you agree?