Bird's opening response - 1.f4 ... d4 2. e3 ... d5

I played a game today and white started out with the bird's opening. I didn't really know much so I decided for a reverse dutch, but I saw the opportunity to ruin his plan on move 2 with d5, after e3. 

I suppose that it is generally considered better to develop, or white can push to e4, but I was wondering if there are any serious issues with pushing to d5?

It seems like a quick easy novelty to put bird's players on the defensive, and to get to playing real chess quickly.

It seems like there was only one game in the chess.com database in 1937, with black winning.

I'm ambivalent towards the Bird.  I mean, it's playable, but 1.d4 achieves the same thing as Bird's opening while both opening lines for pieces and doesn't weaken the kingside.  Here's a sexy line for black against the Bird (no, not another one of my reversed Manhattan Gambit posts though that's a good reply too):

Yeah, I didn't have much trouble, but for some reason I like the idea of pushing the d4 pawn to d5. However, the line you put up is making the creative juices grow. I'll have to give it a shot. Maybe sometime in the next 100 games I'll play the bird once.

Just the simple 3.Nf3 increasing the pressure on d4 looks quite OK.  If Black takes, White can play d4 and recapture with the QB later.  If Black just defends with 3..c5 or 3..Nc6, White can push past with 4.e3-e4, develop with Bc4/Bb5, d3, O-O and get a good game, the same type of game Black gets if he plays the Budapest and White declines with d4-d5.  On 3..Bg4 4.Bc4! already threatening Bxf7+ looks strong.

I see, but if white plays d4, then black en passents to d2, and looks more than fine.

That's not legal.

Maybe I'm not sure, but why isnt it legal? Black has a pawn on the 3 rank, white moves two spaces to the 4th, and passes the black pawn.

Doesn't that allow en passant?

Dang, well don't that beat all. I thought you could en passant any time they moved passed your pawn two squares.