1.032 is way to high for that beer to finish with. That's leaving a ton of fermentables available for bugs, and the alcohol content is not nearly enough to keep the bad guys at bay. What happened is that fermentation stalled out and some bugs have grabbed hold. If you can keg, you could keg it now and drink it before it gets funky. I would definitely not bottle it now, you will have bombs for sure within a week or 3. Not to be pessimistic, but Imperial Stout is not a great style to sour anyway, without a lot of skill. It could get nasty and astringent.