Suddenly, periods / dots in variable values are converted to space

[Chandler]

I don't know why this is suddenly happening, I haven't made any major changes 
to bash or anything else in my shell that I can remember, but I've been working 
around the clock on many things lately, there must be an explanation.  I work 
in a shared home directory and the versions of bash vary from system to system, 
fun I know.  On this particular machine, bash is 4.4.20.  I have some variables 
defined in ~/.bashrc for some files that I frequently reference, for example:

export File1="/dev/sda/file1.txt"

Previously, I could just use a command like `less $File1` and it would bring up 
the file.  Now, the dot in the filename is converted to a space and less tries 
to open 2 separate files:

$ less $File1
/dev/sda/file1: No such file or directory
txt: No such file or directory
$

echo is also affected:
$ echo $File1
/dev/sda/file1 txt
$

I know it's safer to use curly braces and I've been doing that more and more, 
but that doesn't help in this case, returning the same thing as echo.  `set` 
will show that the variable is still defined correctly, however:

$ set | grep File1
File1=/dev/sda/file1.txt
$

To get less or echo to work, now I have to put the variable in double-quotes (e.g. `echo 
"$File1"`).

Any idea what could cause this change in behavior?

Thanks