Control Bids are Tricky

Playing with GiB (BBO) last night, I held this hand:

S AK9
H K2
D 42
C AKQJ74

I opened 1 club. Partner bid 1 diamond. I opted for 3 clubs, which partner raised to 4.

Rightly or wrongly, I decided to make a slam try. I bid 4 spades, and partner bid 5C.

Partner came down with:

S 75
H J854
D AK943
C T2

Slam is 50% on the finesse of the ace of hearts. Granted, partner only having 2 spades helps immensely, but I can't help but feel that this is a slam I want to be in.

I started to wonder if I shouldn't have control bid hearts, but based on some feedback I don't think that this is correct. My 4 spade bid says that:
- I'm interested in slam
- I have spades stopped.

With partner's AK of diamonds, he should know that my diamonds were wide open. However, logically, can my hearts also be wide open? If I was really xx in both reds, would I even be considering slam?

In the end, I don't know if my 4 spade bid was right or wrong. I don't even know if GiB's 5 club bid was right or wrong. The lesson to be learned, I think, is that north should be able to infer at least a partial heart stop in south's hand based on his diamond holding.

I can only hope that I take the time to think this deeply when my partners control bid. Clearly, there's some reasoning and thought involved in the process.