In general, it is difficult to substantially prove spirituality is "taught" in aikido anymore, at least here in the states. I would tend to believe that spirituality is leaking out of aikido just as religion is leaking out of government, public schools and places where religious sensitivity is volatile. The pressure to keep our religious and spiritual beliefs internally is increasing as our society is becoming more critical of religious expression in any context. Public expression of spirituality is intimidating because we expose our more valued beliefs and thoughts for public scrutiny to which many no longer have appreciation or respect. Public expression is an intimidating thing because it holds us accountible for our beliefs through our actions. Humans rationalize all kinds of things, including our spirituality; we will reduce our spiritual commitment to the minimum amount of public commitment to reduce the potential for accountability and scrutiny. How many of us have answered a question under our breath with "I knew that?" The simple fact that you did not express the answer outwardly contradicts your statement. It more appropriate to mutter, "that's what I thought, but I did not say it aloud for fear that I would be wrong and publically accountible for my error."
Aikido is a perfect example of spiritual minimization. O'Sensei was deeply religious, almost (if not) fanantical; he received divine visions, joined a [cult], and believed he was posessed by a god. O'Sensei performed many actions, cleanings, exercises that represented his spiritual belief. Yet we choose to replicate in majority only physical exercises that may be veiled in their purpose. On one hand we claim that aikido is spiritual, yet on the other sheepishly concede that clapping during class is a religious activity from which some students abstain.
The spirituality that O'Sensei possesed and the courage he had to express his spirituality is greater than most of use will ever aspire to obtain. Rather, I believe spirituality is expressed through our actions. If we limit our spiritual expression to physical technique, then by our actions we limit our commitment in spirituality. I am very appreciative of those aikidoka that posess the courage to outwardly express their spiritual beliefs beyond simple exercise.