Do you have your own disposable income or is it all shared? If you have your own then I say don't say anything - just get it if you want it. If all monies are shared then yes, I think you need to discuss it with DH first. That's one nice thing about how my DH and I handle money. After the bills are paid and money is put into savings, his is his and mine is mine - whatever we choose to do with our disposable income isn't questioned by the other. Works out great for us.
As we must account for every idle word, so must we account for every idle silence." ~Benjamin Franklin