Hello,
Sounds like a bug, but if you could post an example, it would help us to better understand the case.
Note that since sprite are using font text color, you can also select it like this:
sprite $foo1 {
FFFFFFFFFFFFFFF
F0123456789ABCF
F0123456789ABCF
F0123456789ABCF
F0123456789ABCF
F0123456789ABCF
F0123456789ABCF
F0123456789ABCF
F0123456789ABCF
FFFFFFFFFFFFFFF
}
Alice -> Bob : Testing <color:red><$foo1></color>