URL in custom BBCode

[mad@Max]

Let's say i wrote my bbcode through a bbcode_create.
All fine, but if i post a link, like [mybb]http://somelink.com/[mybb], link will be parsed after reload page (if it was ajax). And after reload page posted link not will be trimmed.
That doesn't happen, if before of link will be exist a whitespace or a new line, like

[mybb] http://somelink.com/[mybb]
[mybb]
http://somelink.com/[mybb]

It's are the bug or my curves hands?

PS A similar situation can be replicated in the hack BB Code [table].