I Think it goes a little further than that. The smilie won't be read correctly unless there's a leading "space" before it.

For example, after quoting a messege, a user responds with a smilie ,

[ /quote]:smiliecode:

or

[quote ]:smiliecode:[/quote ]

The smilie won't take.

If the user does this

[ quote] :smiliecode: [/quote ]

or

[ /quote] :smiliecode:

it does

The problem exists on either side of a quote tag. The smilie will not engage unless separated by a space.