If you're simply painting it (whether you're using paint or spray bedliner) I'd prolly recommend sanding those bubbles out, then roughing the whole thing before spraying.
If you're Line-Xing, I'd say you're good to go as is.
As you know, I had mine Line-Xed with standard black this spring, and the bumpers and other bits a year or so before that. It starts out really shiny and glossy, but fades into a nice
almost flat, black finish which is very similar to the stock plastic. If you where going black and wanted to keep the shine, they recommend Line-X Xtra; the same goes if you're going to color match.
I have had no problems what-so-ever with any Line-Xed part; whether it was originally black plastic, chrome plastic, fiberglass or metal...the sh!t is GREAT.
Since Line-X is so thick I decided to pop out my grille letters instead of coating over them. If you decide to go that route, know that they are attached with adhesive tape. There's no holes under them. Get a small screwdriver or scraper and work them off. Be careful though if you're going the painting route because you could easily gouge the plastic trying to work these off; but if you're going Line-X don't worry, it's so thick that it'll cover that right up.
