Leaching is a term from the world of chemical fertilizers, because chemical fertilizers contain salt. Leaching only happens with water soluble fertilizers. SBM (and organics, in general) are not water soluble. Therefore you should be fine. It is possible for organic fertilizers to be simply washed away by a heavy rain, if your lawn was on a steep slope, and it rained hard enough to cause heavy runoff. But your SBM had a week or so on the ground before it rained. And your SBM would have begun the process of absorbing moisture, breaking down, and becoming fertilizer by the time it rained. I'm sure in your case, the rain will help it break down even faster, and will help.

While the nutrients in most organic "fertilizers" are not very water soluble there is a fairly decent chance that with that much rain in that short of time span the material itself could have been washed off the soil with the run off of the train.
What affect that much rain would have on soil bacterial activity depends on how long the water remains in the soil.

thank you two for the follow ups

One thing that did leach out is any acidity your soil may have accumulated over the summer and spring (since the rains in Feb). You might keep an eye on it. If it turns yellow it is probably not from lack of fertilizer. It is probably from lack of iron. The only iron supplement that really works for us in SoTex is greensand. You can get it in Austin at John Dromgoole's nursery and probably some other places. Call around.

thanks for the info. how many 40# bags of greensand for 3000sqft bermuda?

Three bags.